Slurry distributor, system, and method for using same

ABSTRACT

A slurry distributor can include a feed conduit and a distribution conduit in fluid communication therewith. The feed conduit can include a first and second feed inlets disposed in spaced relationship to each other. The distribution conduit can extend generally along a longitudinal axis and include an entry portion and a distribution outlet in fluid communication therewith. The entry portion is in fluid communication with the first and second feed inlets of the feed conduit. The distribution outlet extends a predetermined distance along a transverse axis. The first and second feed inlets each has an opening with a cross-sectional area. The entry portion of the distribution conduit has an opening with a cross-sectional area which is greater than the sum of the cross-sectional areas of the openings of the first and second feed inlets. The slurry distributor can be placed in fluid communication with a gypsum slurry mixer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application claims the benefit of priority to U.S.Provisional Patent Application Nos.

-   -   61/550,827, filed Oct. 24, 2011, and entitled, “Slurry        Distributor, System, Method for Using, and Method for Making        Same”;    -   61/550,857, filed Oct. 24, 2011, and entitled, “Flow Splitter        for Slurry Distribution System”; and    -   61/550,873, filed Oct. 24, 2011, and entitled, “Automatic Device        for Squeezing Slurry Splitter,”        which are incorporated in their entireties herein by this        reference.

BACKGROUND

The present disclosure relates to continuous board (e.g., wallboard)manufacturing processes and, more particularly, to an apparatus, systemand method for the distribution of an aqueous calcined gypsum slurry.

It is well-known to produce gypsum board by uniformly dispersingcalcined gypsum (commonly referred to as “stucco”) in water to form anaqueous calcined gypsum slurry. The aqueous calcined gypsum slurry istypically produced in a continuous manner by inserting stucco and waterand other additives into a mixer which contains means for agitating thecontents to form a uniform gypsum slurry. The slurry is continuouslydirected toward and through a discharge outlet of the mixer and into adischarge conduit connected to the discharge outlet of the mixer. Anaqueous foam can be combined with the aqueous calcined gypsum slurry inthe mixer and/or in the discharge conduit. The stream of slurry passesthrough the discharge conduit from which it is continuously depositedonto a moving web of cover sheet material supported by a forming table.The slurry is allowed to spread over the advancing web. A second web ofcover sheet material is applied to cover the slurry and form a sandwichstructure of a continuous wallboard preform, which is subjected toforming, such as at a conventional forming station, to obtain a desiredthickness. The calcined gypsum reacts with the water in the wallboardpreform and sets as the wallboard preform moves down a manufacturingline. The wallboard preform is cut into segments at a point along theline where the wallboard preform has set sufficiently, the segments areflipped over, dried (e.g., in a kiln) to drive off excess water, andprocessed to provide the final wallboard product of desired dimensions.

Prior devices and methods for addressing some of the operationalproblems associated with the production of gypsum wallboard aredisclosed in commonly-assigned U.S. Pat. Nos. 5,683,635; 5,643,510;6,494,609; 6,874,930; 7,007,914; and 7,296,919, which are incorporatedherein by reference.

The weight proportion of water relative to stucco that is combined toform a given amount of finished product is often referred to in the artas the “water-stucco ratio” (WSR). A reduction in the WSR without aformulation change will correspondingly increase the slurry viscosity,thereby reducing the ability of the slurry to spread on the formingtable. Reducing water usage (i.e., lowering the WSR) in the gypsum boardmanufacturing process can yield many advantages, including theopportunity to reduce the energy demand in the process. However,spreading increasingly viscous gypsum slurries uniformly on the formingtable remains a great challenge.

Furthermore, in some situations where the slurry is a multi-phase slurryincluding air, air-liquid slurry separation can develop in the slurrydischarge conduit from the mixer. As WSR decreases, the air volumeincreases to maintain the same dry density. The degree of air phaseseparated from the liquid slurry phase increases, thereby resulting inthe propensity for larger mass or density variation.

It will be appreciated that this background description has been createdby the inventors to aid the reader and is not to be taken as anindication that any of the indicated problems were themselvesappreciated in the art. While the described principles can, in someaspects and embodiments, alleviate the problems inherent in othersystems, it will be appreciated that the scope of the protectedinnovation is defined by the attached claims and not by the ability ofany disclosed feature to solve any specific problem noted herein.

SUMMARY

In one aspect, the present disclosure is directed to embodiments of aslurry distribution system for use in preparing a gypsum product. In oneembodiment, a slurry distributor can include a feed conduit and adistribution conduit in fluid communication therewith. The feed conduitcan include a first feed inlet in fluid communication with thedistribution conduit and a second feed inlet disposed in spacedrelationship with the first feed inlet and in fluid communication withthe distribution conduit. The distribution conduit can extend generallyalong a longitudinal axis and include an entry portion and adistribution outlet in fluid communication therewith. The entry portionis in fluid communication with the first and second feed inlets of thefeed conduit. The distribution outlet extends a predetermined distancealong a transverse axis, which is substantially perpendicular to thelongitudinal axis.

In other embodiments, a slurry distributor includes a feed conduit and adistribution conduit. The feed conduit includes a first entry segmentwith a first feed inlet and a second entry segment with a second feedinlet disposed in spaced relationship to the first feed inlet. Thedistribution conduit extends generally along a longitudinal axis andincludes an entry portion and a distribution outlet in fluidcommunication with the entry portion. The entry portion is in fluidcommunication with the first and second feed inlets of the feed conduit.The distribution outlet extends a predetermined distance along atransverse axis. The transverse axis is substantially perpendicular tothe longitudinal axis. The first and second feed inlets each has anopening with a cross-sectional area. The entry portion of thedistribution conduit has an opening with a cross-sectional area which isgreater than the sum of the cross-sectional areas of the openings of thefirst and second feed inlets.

In other embodiments, a slurry distributor includes a feed conduit, adistribution conduit, and at least one support segment. The feed conduitincludes a first entry segment with a first feed inlet and a secondentry segment with a second feed inlet disposed in spaced relationshipto the first feed inlet. The distribution conduit extends generallyalong a longitudinal axis and includes an entry portion and adistribution outlet in fluid communication with the entry portion. Theentry portion is in fluid communication with the first and second feedinlets of the feed conduit. Each support segment is movable over a rangeof travel such that the support segment is in a range of positions overwhich the support segment is in increasing compressive engagement with aportion of at least one of the feed conduit and the distributionconduit.

In another aspect of the present disclosure, a slurry distributor can beplaced in fluid communication with a gypsum slurry mixer adapted toagitate water and calcined gypsum to form an aqueous calcined gypsumslurry. In one embodiment, the disclosure describes a gypsum slurrymixing and dispensing assembly which includes a gypsum slurry mixeradapted to agitate water and calcined gypsum to form an aqueous calcinedgypsum slurry. A slurry distributor is in fluid communication with thegypsum slurry mixer and is adapted to receive a first flow and a secondflow of aqueous calcined gypsum slurry from the gypsum slurry mixer anddistribute the first and second flows of aqueous calcined gypsum slurryonto an advancing web.

The slurry distributor includes a first feed inlet adapted to receivethe first flow of aqueous calcined gypsum slurry from the gypsum slurrymixer, a second feed inlet adapted to receive the second flow of aqueouscalcined gypsum slurry from the gypsum slurry mixer, and a distributionoutlet in fluid communication with both the first and the second feedinlets and adapted such that the first and second flows of aqueouscalcined gypsum slurry discharge from the slurry distributor through thedistribution outlet.

In other embodiments, a gypsum slurry mixing and dispensing assemblyincludes a mixer and a slurry distributor in fluid communication withthe mixer. The mixer is adapted to agitate water and calcined gypsum toform an aqueous calcined gypsum slurry. The slurry distributor includesa feed conduit and a distribution conduit:

The feed conduit includes a first entry segment with a first feed inletand a second entry segment with a second feed inlet disposed in spacedrelationship to the first feed inlet. The first feed inlet is adapted toreceive a first flow of aqueous calcined gypsum slurry from the gypsumslurry mixer. The second feed inlet is adapted to receive a second flowof aqueous calcined gypsum slurry from the gypsum slurry mixer.

The distribution conduit extends generally along a longitudinal axis andincludes an entry portion and a distribution outlet in fluidcommunication with the entry portion. The entry portion is in fluidcommunication with the first and second feed inlets of the feed conduit.The distribution outlet extends a predetermined distance along atransverse axis. The transverse axis is substantially perpendicular tothe longitudinal axis. The distribution outlet is in fluid communicationwith both the first and the second feed inlets and is adapted such thatthe first and second flows of aqueous calcined gypsum slurry dischargefrom the slurry distributor through the distribution outlet.

The first and second feed inlets each has an opening with across-sectional area. The entry portion of the distribution conduit hasan opening with a cross-sectional area which is greater than the sum ofthe cross-sectional areas of the openings of the first and second feedinlets.

In still another aspect of the present disclosure, the slurrydistribution system can be used in a method of preparing a gypsumproduct. For example, a slurry distributor can be used to distribute anaqueous calcined gypsum slurry upon an advancing web.

In some embodiments, a method of distributing an aqueous calcined gypsumslurry upon a moving web can be performed using a slurry distributorconstructed according to principles of the present disclosure. A firstflow of aqueous calcined gypsum slurry and a second flow of aqueouscalcined gypsum slurry are respectively passed through a first feedinlet and a second feed inlet of the slurry distributor. The first andsecond flows of aqueous calcined gypsum slurry are combined in theslurry distributor. The first and second flows of aqueous calcinedgypsum slurry are discharged from a distribution outlet of the slurrydistributor upon the moving web.

In other embodiments, a method of preparing a gypsum product can beperformed using a slurry distributor constructed according to principlesof the present disclosure. A first flow of aqueous calcined gypsumslurry is passed at an average first feed velocity through a first feedinlet of a slurry distributor. A second flow of aqueous calcined gypsumslurry is passed at an average second feed velocity through a secondfeed inlet of the slurry distributor. The second feed inlet is in spacedrelationship to the first feed inlet. The first and second flows ofaqueous calcined gypsum slurry are combined in the slurry distributor.The combined first and second flows of aqueous calcined gypsum slurryare discharged at an average discharge velocity from a distributionoutlet of the slurry distributor upon a web of cover sheet materialmoving along a machine direction. The average discharge velocity is lessthan the average first feed velocity and the average second feedvelocity.

Embodiments of a mold for use in a method for making a slurrydistributor according to principles of the present disclosure are alsodisclosed herein. Embodiments of supports for a slurry distributoraccording to principles of the present disclosure are also disclosedherein.

Further and alternative aspects and features of the disclosed principleswill be appreciated from the following detailed description and theaccompanying drawings. As will be appreciated, the slurry distributionsystems disclosed herein are capable of being carried out and used inother and different embodiments, and capable of being modified invarious respects. Accordingly, it is to be understood that both theforegoing general description and the following detailed description areexemplary and explanatory only and do not restrict the scope of theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an embodiment of a slurry distributorconstructed in accordance with principles of the present disclosure.

FIG. 2 is a perspective view of the slurry distributor of FIG. 1 and aperspective view of an embodiment of a slurry distributor supportconstructed in accordance with principles of the present disclosure.

FIG. 3 is a front elevational view of the slurry distributor of FIG. 1and the slurry distributor support of FIG. 2.

FIG. 4 is a perspective view of an embodiment of a slurry distributorconstructed in accordance with principles of the present disclosure thatdefines an interior geometry that is similar to the slurry distributorof FIG. 1, but that is constructed from a rigid material and has atwo-piece construction.

FIG. 5 is another perspective view of the slurry distributor of FIG. 4but with a profiling system removed for illustrative purposes.

FIG. 6 is an isometric view of another embodiment of a slurrydistributor constructed in accordance with principles of the presentdisclosure, which includes a first feed inlet and a second feed inletdisposed at about a sixty degree feed angle with respect to alongitudinal axis or machine direction of the slurry distributor.

FIG. 7 is a top plan view of the slurry distributor of FIG. 6.

FIG. 8 is a rear elevational view of the slurry distributor of FIG. 6.

FIG. 9 is a top plan view of a first piece of the slurry distributor ofFIG. 6, which has a two-piece construction.

FIG. 10 is a front perspective view of the slurry distributor piece ofFIG. 9.

FIG. 11 is an exploded view of the slurry distributor of FIG. 6 and asupport system for the slurry distributor constructed in accordance withprinciples of the present disclosure.

FIG. 12 is a perspective view of the slurry distributor and the supportsystem of FIG. 11.

FIG. 13 is an exploded view of the slurry distributor of FIG. 6 andanother embodiment of a support system constructed in accordance withprinciples of the present disclosure.

FIG. 14 is a perspective view of the slurry distributor and the supportsystem of FIG. 13.

FIG. 15 is a perspective view of an embodiment of a slurry distributorconstructed in accordance with principles of the present disclosure thatdefines an interior geometry that is similar to the slurry distributorof FIG. 6, but that is constructed from a flexible material and has anintegral construction.

FIG. 16 is a top plan view of the slurry distributor of FIG. 15.

FIG. 17 is an enlarged, perspective view of the interior geometrydefined by the slurry distributor of FIG. 15, illustrating progressivecross-sectional flow areas of a portion of the feed conduit thereof.

FIG. 18 is an enlarged, perspective view of the interior geometry of theslurry distributor of FIG. 15, illustrating another progressivecross-sectional flow area of the feed conduit.

FIG. 19 is an enlarged, perspective view of the interior geometry of theslurry distributor of FIG. 15, illustrating yet another progressivecross-sectional flow area of the feed conduit which is aligned with ahalf of an entry portion to a distribution conduit of the slurrydistributor of FIG. 15.

FIG. 20 is a perspective view of the slurry distributor of FIG. 15 andanother embodiment of a support system constructed in accordance withprinciples of the present disclosure.

FIG. 21 is a perspective view as in FIG. 20, but with a support frameremoved for illustrative purposes to show a plurality of retainingplates in distributed relationship with the slurry distributor of FIG.15.

FIG. 22 is a perspective view of an embodiment of a multi-piece mold formaking a slurry distributor as in FIG. 1 constructed in accordance withprinciples of the present disclosure.

FIG. 23 is a top plan view of the mold of FIG. 22.

FIG. 24 is an exploded view of an embodiment of a multi-piece mold formaking a slurry distributor as in FIG. 15 constructed in accordance withprinciples of the present disclosure.

FIG. 25 is a perspective view of another embodiment of a mold for makinga piece of a two-piece slurry distributor constructed in accordance withprinciples of the present disclosure.

FIG. 26 is a top plan view of the mold of FIG. 25.

FIG. 27 is a schematic plan diagram of an embodiment of a gypsum slurrymixing and dispensing assembly including a slurry distributor inaccordance with principles of the present disclosure.

FIG. 28 is a schematic plan diagram of another embodiment of a gypsumslurry mixing and dispensing assembly including a slurry distributor inaccordance with principles of the present disclosure.

FIG. 29 is a schematic elevational diagram of an embodiment of a wet endof a gypsum wallboard manufacturing line in accordance with principlesof the present disclosure.

FIG. 30 is a perspective view of an embodiment of a flow splitterconstructed in accordance with principles of the present disclosuresuitable for use in a gypsum slurry mixing and dispensing assemblyincluding a slurry distributor.

FIG. 31 is a side elevational view, in section, of the flow splitter ofFIG. 30.

FIG. 32 is a side elevational view of the flow splitter of FIG. 30 withan embodiment of a squeezing apparatus constructed in accordance withprinciples of the present disclosure mounted thereto.

FIG. 33 is a top plan view of a half portion of a slurry distributorsimilar to the slurry distributor of FIG. 15.

FIG. 34 is a plot of the data from Table I of Example 1 showing thedimensionless distance from the feed inlet versus the dimensionless areaand the dimensionless hydraulic radius of the half portion of the slurrydistributor of FIG. 33.

FIG. 35 is a plot of the data from Tables II and III of Examples 2 and3, respectively, showing the dimensionless distance from the feed inletversus the dimensionless velocity of a flow of modeled slurry movingthrough the half portion of the slurry distributor of FIG. 33.

FIG. 36 is a plot of the data from Tables II and III of Examples 2 and3, respectively, showing the dimensionless distance from the feed inletversus the dimensionless shear rate in the modeled slurry moving throughthe half portion of the slurry distributor of FIG. 33.

FIG. 37 is a plot of the data from Tables II and III of Examples 2 and3, respectively, showing the dimensionless distance from the feed inletversus the dimensionless viscosity of the modeled slurry moving throughthe half portion of the slurry distributor of FIG. 33.

FIG. 38 is a plot of the data from Tables II and III of Examples 2 and3, respectively, showing the dimensionless distance from the feed inletversus the dimensionless shear stress in the modeled slurry movingthrough the half portion of the slurry distributor of FIG. 33.

FIG. 39 is a plot of the data from Tables II and III of Examples 2 and3, respectively, showing the dimensionless distance from the feed inletversus the dimensionless Reynolds number of the modeled slurry movingthrough the half portion of the slurry distributor of FIG. 33.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The present disclosure provides various embodiments of a slurrydistribution system that can be used in the manufacture of products,including cementitious products such as gypsum wallboard, for example.Embodiments of a slurry distributor constructed in accordance withprinciples of the present disclosure can be used in a manufacturingprocess to effectively distribute a multi-phase slurry, such as onecontaining air and liquid phases, such as found in an aqueous foamedgypsum slurry, for example.

Embodiments of a distribution system constructed in accordance withprinciples of the present disclosure can be used to distribute a slurry(e.g., an aqueous calcined gypsum slurry) onto an advancing web (e.g.,paper or mat) moving on a conveyor during a continuous board (e.g.,wallboard) manufacturing process. In one aspect, a slurry distributionsystem constructed in accordance with principles of the presentdisclosure can be used in a conventional gypsum drywall manufacturingprocess as, or part of, a discharge conduit attached to a mixer adaptedto agitate calcined gypsum and water to form an aqueous calcined gypsumslurry.

Embodiments of a slurry distribution system constructed in accordancewith principles of the present disclosure are aimed at accomplishingwider distribution (along the cross-machine direction) of a uniformgypsum slurry. Embodiments of a slurry distribution system of thepresent disclosure are suitable for use with a gypsum slurry having arange of WSRs, including WSRs conventionally used to manufacture gypsumwallboard and those that are relatively lower and have a relativelyhigher viscosity. Furthermore, a gypsum slurry distribution system ofthe present disclosure can be used to help control air-liquid phaseseparation, such as, in aqueous foamed gypsum slurry, including foamedgypsum slurry having a very high foam volume. The spreading of theaqueous calcined gypsum slurry over the advancing web can be controlledby routing and distributing the slurry using a distribution system asshown and described herein.

Embodiments of a method of preparing a gypsum product in accordance withprinciples of the present disclosure can include distributing an aqueouscalcined gypsum slurry upon an advancing web using a slurry distributorconstructed in accordance with principles of the present disclosure.Various embodiments of a method of distributing an aqueous calcinedgypsum slurry upon a moving web are described herein.

Turning now to the Figures, there is shown in FIGS. 1-3 an embodiment ofa slurry distributor 120 according to principles of the presentdisclosure, and in FIGS. 4 and 5, another embodiment of a slurrydistributor 220 according to principles of the present disclosure isshown. The slurry distributor 120 shown in FIGS. 1-3 is constructed froma resiliently flexible material, whereas the slurry distributor 220shown in FIGS. 3 and 4 is made from a relatively rigid material.However, the interior flow geometry of both slurry distributors 120, 220in FIGS. 1-5 is the same, and reference should also be made to FIG. 5when considering the slurry distributor 120 of FIGS. 1-3.

Referring to FIG. 1, the slurry distributor 120 includes a feed conduit122, which has first and second feed inlets 124, 125, and a distributionconduit 128, which includes a distribution outlet 130 and is in fluidcommunication with the feed conduit 128. A profiling system 132 (seeFIG. 3) adapted to locally vary the size of the distribution outlet 130of the distribution conduit 128 can also be provided.

Referring to FIG. 1, the feed conduit 122 extends generally along atransverse axis or cross-machine direction 60, which is substantiallyperpendicular to a longitudinal axis or machine direction 50. The firstfeed inlet 124 is in spaced relationship with the second feed inlet 125.The first feed inlet 124 and the second feed inlet 125 define respectiveopenings 134, 135 that have substantially the same area. The illustratedopenings 134, 135 of the first and second feed inlets 124, 125 both havea circular cross-sectional shape as illustrated in this example. Inother embodiments, the cross-sectional shape of the feed inlets 124, 125can take other forms, depending upon the intended applications andprocess conditions present.

The first and second feed inlets 124, 125 are in opposing relationshipto each other along the cross-machine axis 60 such that the first andsecond feed inlets 124, 125 are disposed at substantially a 90° angle tothe machine axis 50. In other embodiments the first and second feedinlets 124, 125 can be oriented in a different manner with respect tothe machine direction. For example, in some embodiments, the first andsecond feed inlets 124, 125 can be at an angle between 0° and about 135°with respect to the machine direction 50.

The feed conduit 122 includes first and second entry segments 136, 137and a bifurcated connector segment 139 disposed between the first andsecond entry segments 136, 137. The first and second entry segments 136,137 are generally cylindrical and extend along the transverse axis 60such that they are substantially parallel to a plane 57 defined by thelongitudinal axis 50 and the transverse axis 60. The first and secondfeed inlets 124, 125 are disposed at the distal ends of the first andthe second entry segments 136, 137, respectively, and are in fluidcommunication therewith.

In other embodiments the first and second feed inlets 124, 125 and thefirst and second entry segments 136, 137 can be oriented in a differentmanner with respect to the transverse axis 60, the machine direction 50,and/or the plane 57 defined by the longitudinal axis 50 and thetransverse axis 60. For example, in some embodiments, the first andsecond feed inlets 124, 125 and the first and second entry segments 136,137 can each be disposed substantially in the plane 57 defined by thelongitudinal axis 50 and the transverse axis 60 at a feed angle θ withrespect to the longitudinal axis or machine direction 50 which is anangle in a range up to about 135° with respect to the machine direction50, and in other embodiments in a range from about 30° to about 135°,and in yet other embodiments in a range from about 45° to about 135°,and in still other embodiments in a range from about 40° to about 110°.

The bifurcated connector segment 139 is in fluid communication with thefirst and second feed inlets 124, 125 and the first and the second entrysegments 136, 137. The bifurcated connector segment 139 includes firstand second shaped ducts 141, 143. The first and second feed inlets 124,125 of the feed conduit 22 are in fluid communication with the first andsecond shaped ducts 141, 143, respectively. The first and second shapedducts 141, 143 of the connector segment 139 are adapted to receive afirst flow in a first feed direction 190 and a second flow in a secondflow direction 191 of aqueous calcined gypsum slurry from the first andsecond feed inlets 124, 125, respectively, and to direct the first andsecond flows 190, 191 of aqueous calcined gypsum slurry into thedistribution conduit 128.

As shown in FIG. 5, the first and second shaped ducts 141, 143 of theconnector segment 139 define first and second feed outlets 140, 145respectively in fluid communication with the first and second feedinlets 124, 125. Each feed outlet 140, 145 is in fluid communicationwith the distribution conduit 128. Each of the illustrated first andsecond feed outlets 140, 145 defines an opening 142 with a generallyrectangular inner portion 147 and a substantially circular side portion149. The circular side portions 145 are disposed adjacent side walls151, 153 of the distribution conduit 128.

In embodiments, the openings 142 of the first and second feed outlets140, 145 can have a cross-sectional area that is larger than thecross-sectional area of the openings 134, 135 of the first feed inlet124 and the second feed inlet 125, respectively. For example, in someembodiments, the cross-sectional area of the openings 142 of the firstand second feed outlets 140, 145 can be in a range from greater than toabout 300% greater than the cross-sectional area of the openings 134,135 of the first feed inlet 124 and the second feed inlet 125,respectively, in a range from greater than to about 200% greater inother embodiments, and in a range from greater than to about 150%greater in still other embodiments.

In embodiments, the openings 142 of the first and second feed outlets140, 145 can have a hydraulic diameter (4×cross-sectionalarea/perimeter) that is smaller than the hydraulic diameter of theopenings 134, 135 of the first feed inlet 124 and the second feed inlet125, respectively. For example, in some embodiments, the hydraulicdiameter of the openings 142 of the first and second feed outlets 140,145 can be about 80% or less than the hydraulic diameter of the openings134, 135 of the first feed inlet 124 and the second feed inlet 125,respectively, about 70% or less in other embodiments, and about 50% orless in still other embodiments

Referring back to FIG. 1, the connector segment 139 is substantiallyparallel to the plane 57 defined by the longitudinal axis 50 and thetransverse axis 60. In other embodiments the connector segment 139 canbe oriented in a different manner with respect to the transverse axis60, the machine direction 50, and/or the plane 57 defined by thelongitudinal axis 50 and the transverse axis 60.

The first feed inlet 124, the first entry segment 136, and the firstshaped duct 141 are a mirror image of the second feed inlet 125, thesecond entry segment 137, and the second shaped duct 143, respectively.Accordingly, it will be understood that the description of one feedinlet is applicable to the other feed inlet, the description of oneentry segment is applicable to the other entry segment, and thedescription of one shaped duct is applicable to the other shaped duct,as well in a corresponding manner.

The first shaped duct 141 is fluidly connected to the first feed inlet124 and the first entry segment 136. The first shaped duct 141 is alsofluidly connected to the distribution conduit 128 to thereby helpfluidly connect the first feed inlet 124 and the distribution outlet 130such that the first flow 190 of slurry can enter the first feed inlet124; travel through the first entry segment 136, the first shaped duct141, and the distribution conduit 128; and be discharged from the slurrydistributor 120 through the distribution outlet 130.

The first shaped duct 141 has a front, outer curved wall 157 and anopposing rear, inner curved wall 158 defining a curved guide surface 165adapted to redirect the first flow of slurry from the first feed flowdirection 190, which is substantially parallel to the transverse orcross-machine direction 60, to an outlet flow direction 192, which issubstantially parallel to the longitudinal axis or machine direction 50and substantially perpendicular to the first feed flow direction 190.The first shaped duct 141 is adapted to receive the first flow of slurrymoving in the first feed flow direction 190 and redirect the slurry flowdirection by a change in direction angle α, as shown in FIG. 9, suchthat the first flow of slurry is conveyed into the distribution conduit128 moving substantially in the outlet flow direction 192.

In use, the first flow of aqueous calcined gypsum slurry passes throughthe first feed inlet 124 in the first feed direction 190, and the secondflow of aqueous calcined gypsum slurry passes through the second feedinlet 125 in the second feed direction 191. The first and second feeddirections 190, 191 can be symmetrical with respect to each other alongthe longitudinal axis 50 in some embodiments. The first flow of slurrymoving in the first feed flow direction 190 is redirected in the slurrydistributor 120 through a change in direction angle α in a range up toabout 135° to the outlet flow direction 192. The second flow of slurrymoving in the second feed flow direction 191 is redirected in the slurrydistributor 120 through a change in direction angle α in a range up toabout 135° to the outlet flow direction 192. The combined first andsecond flows 190, 191 of aqueous calcined gypsum slurry discharge fromthe slurry distributor 120 moving generally in the outlet flow direction192. The outlet flow direction 192 can be substantially parallel to thelongitudinal axis or machine direction 50.

For example, in the illustrated embodiment, the first flow of slurry isredirected from the first feed flow direction 190 along thecross-machine direction 60 through a change in direction angle α ofabout ninety degrees about the vertical axis 55 to the outlet flowdirection 192 along the machine direction 50. In some embodiments, theflow of slurry can be redirected from a first feed flow direction 190through a change in direction angle α about the vertical axis 55 whichis in a range up to about 135° to the outlet flow direction 192, and inother embodiments in a range from about 30° to about 135°, and in yetother embodiments in a range from about 45° to about 135°, and in stillother embodiments in a range from about 40° to about 110°.

In some embodiments, the shape of the rear curved guide surface 165 canbe generally parabolic, which in the illustrated embodiment can bedefined by a parabola of the form Ax²+B. In alternate embodiments,higher order curves may be used to define the rear curved guide surface165 or, alternatively, the rear, inner wall 158 can have a generallycurved shape that is made up of straight or linear segments that havebeen oriented at their ends to collectively define a generally curvedwall. Moreover, the parameters used to define the specific shape factorsof the outer wall can depend on specific operating parameters of theprocess in which the slurry distributor will be used.

At least one of the feed conduit 122 and the distribution conduit 128can include an area of expansion having a cross-sectional flow area thatis greater than a cross-sectional flow area of an adjacent area upstreamfrom the area of expansion in a direction from the feed conduit 122toward the distribution conduit 128. The first entry segment 136 and/orthe first shaped duct 141 can have a cross section that varies along thedirection of flow to help distribute the first flow of slurry movingtherethrough. The shaped duct 141 can have a cross sectional flow areathat increases in a first flow direction 195 from the first feed inlet124 toward the distribution conduit 128 such that the first flow ofslurry is decelerated as it passes through the first shaped duct 141. Insome embodiments, the first shaped duct 141 can have a maximumcross-section flow area at a predetermined point along the first flowdirection 195 and decrease from the maximum cross-sectional flow area atpoints further along the first flow direction 195.

In some embodiments, the maximum cross-sectional flow area of the firstshaped duct 141 is about 200% of the cross-sectional area of the opening134 of the first feed inlet 124 or less. In yet other embodiments, themaximum cross-sectional flow area of the shaped duct 141 is about 150%of the cross-sectional area of the opening 134 of the first feed inlet124 or less. In still other embodiments, the maximum cross-sectionalflow area of the shaped duct 141 is about 125% of the cross-sectionalarea of the opening 134 of the first feed inlet 124 or less. In yetother embodiments, the maximum cross-sectional flow area of the shapedduct 141 is about 110% of the cross-sectional area of the opening 134 ofthe first feed inlet 124 or less. In some embodiments, thecross-sectional flow area is controlled such that the flow area does notvary more than a predetermined amount over a given length to helpprevent large variations in the flow regime.

In some embodiments, the first entry segment 136 and/or the first shapedduct 141 can include one or more guide channels 167, 168 that areadapted to help distribute the first flow of slurry toward the outerand/or the inner walls 157, 158 of the feed conduit 122. The guidechannels 167, 168 are adapted to increase the flow of slurry around theboundary wall layers of the slurry distributor 120.

Referring to FIGS. 1 and 5, the guide channels 167, 168 can beconfigured to have a larger cross-sectional area than an adjacentportion 171 of the feed conduit 122 which defines a restriction thatpromotes flow to the adjacent guide channel 167, 168 respectivelydisposed at the wall region of the slurry distributor 120. In theillustrated embodiment, the feed conduit 122 includes the outer guidechannel 167 adjacent the outer wall 157 and the sidewall 151 of thedistribution conduit 128 and the inner guide channel 168 adjacent theinner wall 158 of the first shaped duct 141. The cross-sectional areasof the outer and inner guide channels 167, 168 can become progressivelysmaller moving in the first flow direction 195. The outer guide channel167 can extend substantially along the sidewall 151 of the distributionconduit 128 to the distribution outlet 130. At a given cross-sectionallocation through the first shaped duct 141 in a direction perpendicularto the first flow direction 195, the outer guide channel 167 has alarger cross-sectional area than the inner guide channel 168 to helpdivert the first flow of slurry from its initial line of movement in thefirst feed direction 190 toward the outer wall 157.

Providing guide channels adjacent wall regions can help direct or guideslurry flow to those regions, which can be areas in conventional systemswhere “dead spots” of low slurry flow are found. By encouraging slurryflow at the wall regions of the slurry distributor 120 through theprovision of guide channels, slurry buildup inside the slurrydistributor is discouraged and the cleanliness of the interior of theslurry distributor 120 can be enhanced. The frequency of slurry buildupbreaking off into lumps which can tear the moving web of cover sheetmaterial can also be decreased.

In other embodiments, the relative sizes of the outer and inner guidechannels 167, 168 can be varied to help adjust the slurry flow toimprove flow stability and reduce the occurrence of air-liquid slurryphase separation. For example, in applications using a slurry that isrelatively more viscous, at a given cross-sectional location through thefirst shaped duct 141 in a direction perpendicular to the first flowdirection 195, the outer guide channel 167 can have a smallercross-sectional area than the inner guide channel 168 to help urge thefirst flow of slurry toward the inner wall 158.

The inner curved walls 158 of the first and second shaped ducts 141, 142meet to define a peak 175 adjacent an entry portion 152 of thedistribution conduit 128. The peak 175 effectively bifurcates theconnector segment 139. Each feed outlet 140, 145 is in fluidcommunication with the entry portion 152 of the distribution conduit128.

The location of the peak 175 along the longitudinal axis 50 can vary inother embodiments. For example, the inner curved walls 158 of the firstand second shaped ducts 141, 142 can be less curved in other embodimentssuch that the peak 175 is further away from the distribution outlet 130along the longitudinal axis 50 than as shown in the illustrated slurrydistributor 120. In other embodiments, the peak 175 can be closer to thedistribution outlet 130 along the longitudinal axis 50 than as shown inthe illustrated slurry distributor 120.

The distribution conduit 128 is substantially parallel to the plane 57defined by the longitudinal axis 50 and the transverse axis 60 and isadapted to urge the combined first and second flows of aqueous calcinedgypsum slurry from the first and second shaped ducts 141, 142 into agenerally two-dimensional flow pattern for enhanced stability anduniformity. The distribution outlet 130 has a width that extends apredetermined distance along the transverse axis 60 and a height thatextends along a vertical axis 55, which is mutually perpendicular to thelongitudinal axis 50 and the transverse axis 60. The height of thedistribution outlet 130 is small relative to its width. The distributionconduit 128 can be oriented relative to a moving web of cover sheet upona forming table such that the distribution conduit 128 is substantiallyparallel to the moving web.

The distribution conduit 128 extends generally along the longitudinalaxis 50 and includes the entry portion 152 and the distribution outlet130. The entry portion 152 is in fluid communication with the first andsecond feed inlets 124, 125 of the feed conduit 122. Referring to FIG.5, the entry portion 152 is adapted to receive both the first and thesecond flows of aqueous calcined gypsum slurry from the first and secondfeed inlets 124, 125 of the feed conduit 122. The entry portion 152 ofthe distribution conduit 128 includes a distribution inlet 154 in fluidcommunication with the first and second feed outlets 140, 145 of thefeed conduit 122. The illustrated distribution inlet 154 defines anopening 156 that substantially corresponds to the openings 142 of thefirst and second feed outlets 140, 145. The first and second flows ofaqueous calcined gypsum slurry combine in the distribution conduit 128such that the combined flows move generally in the outlet flow direction192 which can be substantially aligned with the line of movement of aweb of cover sheet material moving over a forming table in a wallboardmanufacturing line.

The distribution outlet 130 is in fluid communication with the entryportion 152 and thus the first and second feed inlets 124, 125 and thefirst and second feed outlets 140, 145 of the feed conduit 122. Thedistribution outlet 130 is in fluid communication with the first andsecond shaped ducts 141, 143 and is adapted to discharge the combinedfirst and second flows of slurry therefrom along the outlet flowdirection 192 upon a web of cover sheet material advancing along themachine direction 50.

Referring to FIG. 1, the illustrated distribution outlet 130 defines agenerally rectangular opening 181 with semi-circular narrow ends 183,185. The semi-circular ends 183, 185 of the opening 181 of thedistribution outlet 130 can be the terminating end of the outer guidechannels 167 disposed adjacent the side walls 151, 153 of thedistribution conduit 128.

The opening 181 of the distribution outlet 130 has an area which isgreater than the sum of the areas of the openings 134, 135 of the firstand second feed inlets 124, 125 and is smaller than the area of the sumof the openings 142 of the first and second feed outlets 140, 145 (i.e.,the opening 156 of the distribution inlet 154). Accordingly, thecross-sectional area of the opening 156 of the entry portion 152 of thedistribution conduit 128 is greater than the cross-sectional area of theopening 181 of the distribution outlet 130.

For example, in some embodiments, the cross-sectional area of theopening 181 of the distribution outlet 130 can be in a range fromgreater than to about 400% greater than the sum of the cross-sectionalareas of the openings 134, 135 of the first and second feed inlets 124,125, in a range from greater than to about 200% greater in otherembodiments, and in a range from greater than to about 150% greater instill other embodiments. In other embodiments, the ratio of the sum ofthe cross-sectional areas of the openings 134, 135 of the first andsecond feed inlets 124, 125 to the cross-sectional area of the opening181 of the distribution outlet 130 can be varied based upon one or morefactors, including the speed of the manufacturing line, the viscosity ofthe slurry being distributed by the distributor 120, the width of theboard product being made with the distributor 120, etc. In someembodiments, the cross-sectional area of the opening 156 of the entryportion 152 of the distribution conduit 128 can be in a range fromgreater than to about 200% greater than the cross-sectional area of theopening 181 of the distribution outlet 130, in a range from greater thanto about 150% greater in other embodiments, and in a range from greaterthan to about 125% greater in still other embodiments.

The distribution outlet 130 extends substantially along the transverseaxis 60. The opening 181 of the distribution outlet 130 has a width W₁of about twenty-four inches along the transverse axis 60 and a height H₁of about one inch along the vertical axis 55 (see FIG. 3, also). Inother embodiments, the size and shape of the opening 181 of thedistribution outlet 130 can be varied.

The distribution outlet 130 is disposed intermediately along thetransverse axis 60 between the first feed inlet 124 and the second feedinlet 125 such that the first feed inlet 124 and the second feed inlet125 are disposed substantially the same distance D₁, D₂ from atransverse central midpoint 187 of the distribution outlet 130 (see FIG.3, also). The distribution outlet 130 can be made from a resilientlyflexible material such that its shape is adapted to be variable alongthe transverse axis 60, such as by the profiling system 32, for example.

It is contemplated that the width W₁ and/or height H₁ of the opening 181of the distribution outlet 130 can be varied in other embodiments fordifferent operating conditions. In general, the overall dimensions ofthe various embodiments for slurry distributors as disclosed herein canbe scaled up or down depending on the type of product being manufactured(for example, the thickness and/or width of manufactured product), thespeed of the manufacturing line being used, the rate of deposition ofthe slurry through the distributor, the viscosity of the slurry, and thelike. For example, the width W₁, along the transverse axis 60, of thedistribution outlet 130 for use in a wallboard manufacturing process,which conventionally is provided in nominal widths no greater thanfifty-four inches, can be within a range from about eight to aboutfifty-four inches in some embodiments, and in other embodiments within arange from about eighteen inches to about thirty inches. In otherembodiments, the ratio of the width W₁, along the transverse axis 60, ofthe distribution outlet 130 to the maximum nominal width of the panelbeing produced on the manufacturing system using the slurry distributorconstructed according to principles of the present disclosure can be ina range from about 1/7 to about 1, in a range from about ⅓ to about 1 inother embodiments, in a range from about ⅓ to about ⅔ in yet otherembodiments, and in a range from about ½ to about 1 in still otherembodiments.

The height of the distribution outlet can be within a range from about3/16 inch to about two inches in some embodiments, and in otherembodiments between about 3/16 inch and about an inch. In someembodiments including a rectangular distribution outlet, the ratio ofthe rectangular width to the rectangular height of the outlet openingcan be about 4 or more, in other embodiments about 8 or more, in someembodiments from about 4 to about 288, in other embodiments from about 9to about 288, in other embodiments from about 18 to about 288, and instill other embodiments from about 18 to about 160.

The distribution conduit 128 includes a converging portion 182 in fluidcommunication with the entry portion 152. The height of the convergingportion 182 is less than the height at the maximum cross-sectional flowarea of the first and second shaped ducts 141, 143 and less than theheight of the opening 181 of the distribution outlet 130. In someembodiments, the height of the converging portion 182 can be about halfthe height of the opening 181 of the distribution outlet 130.

The converging portion 182 and the height of the distribution outlet 130can cooperate together to help control the average velocity of thecombined first and second flows of aqueous calcined gypsum beingdistributed from the distribution conduit 128. The height and/or widthof the distribution outlet 130 can be varied to adjust the averagevelocity of the combined first and second flows of slurry dischargingfrom the slurry distributor 120.

In some embodiments, the outlet flow direction 192 is substantiallyparallel to the plane 57 defined by the machine direction 50 and thetransverse cross-machine direction 60 of the system transporting theadvancing web of cover sheet material. In other embodiments, the firstand second feed directions 190, 191 and the outlet flow direction 192are all substantially parallel to the plane 57 defined by the machinedirection 50 and the transverse cross-machine direction 60 of the systemtransporting the advancing web of cover sheet material. In someembodiments, the slurry distributor can be adapted and arranged withrespect to the forming table such that the flow of slurry is redirectedin the slurry distributor 120 from the first and second feed directions190, 191 to the outlet flow direction 192 without undergoing substantialflow redirection by rotating about the cross-machine direction 60.

In some embodiments, the slurry distributor can be adapted and arrangedwith respect to the forming table such that the first and second flowsof slurry are redirected in the slurry distributor from the first andsecond feed directions 190, 191 to the outlet flow direction 192 byredirecting the first and second flows of slurry by rotating about thecross-machine direction 60 over an angle of about forty-five degrees orless. Such a rotation can be accomplished in some embodiments byadapting the slurry distributor such that the first and second feedinlets 124, 125 and the first and second feed directions 190, 191 of thefirst and second flows of slurry are disposed at a vertical offset angleω with respect to the vertical axis 55 and the plane 57 formed by themachine axis 50 and the cross-machine axis 60. In embodiments, the firstand second feed inlets 124, 125 and the first and second feed directions190, 191 of the first and second flows of slurry can be disposed at avertical offset angle ω within a range from zero to about sixty degreessuch that the flow of slurry is redirected about the machine axis 50 andmoves along the vertical axis 55 in the slurry distributor 120 from thefirst and second feed directions 190, 191 to the outlet flow direction192. In embodiments, at least one of the respective entry segment 136,137 and the shaped ducts 141, 143 can be adapted to facilitate theredirection of the slurry about the machine axis 50 and along thevertical axis 55. In embodiments, the first and second flows of slurrycan be redirected from the first and second feed directions 190, 191through a change in direction angle α about an axis substantiallyperpendicular to vertical offset angle ω and/or one or more otherrotational axes within a range of about forty-five degrees to about onehundred fifty degrees to the outlet flow direction 192 such that theoutlet flow direction 192 is generally aligned with the machinedirection 50.

In use, first and second flows of aqueous calcined gypsum slurry passthrough the first and second feed inlets 124, 125 in converging firstand second feed directions 190, 191. The first and second shaped ducts141, 143 redirect the first and second flows of slurry from the firstfeed direction 190 and the second feed direction 191 so that the firstand second flows of slurry move over a change in direction angle α fromboth being substantially parallel to the transverse axis 60 to bothbeing substantially parallel to the machine direction 50. Thedistribution conduit 128 can be positioned such that it extends alongthe longitudinal axis 50 which substantially coincides with the machinedirection 50 along which a web of cover sheet material moves in a methodmaking a gypsum board. The first and second flows of aqueous calcinedgypsum slurry combine in the slurry distributor 120 such that thecombined first and second flows of aqueous calcined gypsum slurry passthrough the distribution outlet 130 in the outlet flow direction 192generally along the longitudinal axis 50 and in the direction of themachine direction.

Referring to FIG. 2, a slurry distributor support 100 can be provided tohelp support the slurry distributor 120, which in the illustratedembodiment is made from a flexible material, such as PVC or urethane,for example. The slurry distributor support 100 can be made from asuitable rigid material to help support the flexible slurry distributor120. The slurry distributor support 100 can include a two-piececonstruction. The two pieces 101, 103 can be pivotally movable withrespect to each other about a hinge 105 at the rear end thereof to allowfor ready access to an interior 107 of the support 100. The interior 107of the support 100 can be configured such that the interior 107substantially conforms to the exterior of the slurry distributor 120 tohelp limit the amount of movement the slurry distributor 120 can undergowith respect to the support 100 and/or to help define the interiorgeometry of the slurry distributor 120 through which a slurry will flow.

Referring to FIG. 3, in some embodiments, the slurry distributor support100 can be made from a suitable resiliently flexible material thatprovides support and is able to be deformed in response to the profilingsystem 132 mounted to the support 100. The profiling system 132 can bemounted to the support 100 adjacent the distribution outlet 130 of theslurry distributor 120. The profiling system 132 so installed can act tovary the size and/or shape of the distribution outlet 130 of thedistribution conduit 128 by also varying the size and/or shape of theclosely conforming support 100, which in turn, influences the sizeand/or shape of the distribution outlet 130.

Referring to FIG. 3, the profiling system 132 can be adapted toselectively change the size and/or shape of the opening 181 of thedistribution outlet 130. In some embodiments, the profiling system canbe used to selectively adjust the height H₁ of the opening 181 of thedistribution outlet 130.

The illustrated profiling system 132 includes a plate 90, a plurality ofmounting bolts 92 securing the plate to the distribution conduit 128,and a series of adjustment bolts 94, 95 threadingly secured thereto. Themounting bolts 92 are used to secure the plate 90 to the support 100adjacent the distribution outlet 130 of the slurry distributor 120. Theplate 90 extends substantially along the transverse axis 60. In theillustrated embodiment, the plate 90 is in the form of a length of angleiron. In other embodiments, the plate 90 can have different shapes andcan comprise different materials. In still other embodiments, theprofiling system can include other components adapted to selectivelychange the size and/or shape of the opening 181 of the distributionoutlet 130.

The illustrated profiling system 132 is adapted to locally vary alongthe transverse axis 60 the size and/or shape of the opening 181 of thedistribution outlet 130. The adjustment bolts 94, 95 are in regular,spaced relationship to each other along the transverse axis 60 over thedistribution outlet 130. The adjustment bolts 94, 95 are independentlyadjustable to locally vary the size and/or shape of the distributionoutlet 130.

The profiling system 132 can be used to locally vary the distributionoutlet 130 so as to alter the flow pattern of the combined first andsecond flows of aqueous calcined gypsum slurry being distributed fromthe slurry distributor 120. For example, the mid-line adjustment bolt 95can be tightened down to constrict the transverse central midpoint 187of the distribution outlet 130 to increase the edge flow angle away fromthe longitudinal axis 50 to facilitate spreading in the cross-machinedirection 60 and to improve the slurry flow uniformity in thecross-machine direction 60.

The profiling system 132 can be used to vary the size of thedistribution outlet 130 along the transverse axis 60 and maintain thedistribution outlet 130 in the new shape. The plate 90 can be made froma material that is suitably strong such that the plate 90 can withstandopposing forces exerted by the adjustment bolts 94, 95 in response toadjustments made by the adjustment bolts 94, 95 in urging thedistribution outlet 130 into a new shape. The profiling system 132 canbe used to help even out variations in the flow profile of the slurry(for example, as a result of different slurry densities and/or differentfeed inlet velocities) being discharged from the distribution outlet 130such that the exit pattern of the slurry from the distribution conduit128 is more uniform.

In other embodiments, the number of adjustment bolts can be varied suchthat the spacing between adjacent adjustment bolts changes. In otherembodiments, such as where the width W₁ of the distribution outlet 130is different, the number of adjustment bolts can also be varied toachieve a desired adjacent bolt spacing. In yet other embodiments, thespacing between adjacent bolts can vary along the transverse axis 60,for example to provide greater locally-varying control at the side edges183, 185 of the distribution outlet 130.

A slurry distributor constructed in accordance with principles of thepresent disclosure can comprise any suitable material. In someembodiments, a slurry distributor can comprise any suitablesubstantially rigid material which can include a suitable material whichcan allow the size and shape of the outlet to be modified using aprofile system, for example. For example, a suitably rigid plastic, suchas ultra-high molecular weight (UHMW) plastic, or metal can be used. Inother embodiments, a slurry distributor constructed in accordance withprinciples of the present disclosure can be made from a flexiblematerial, such as a suitable flexible plastic material, including polyvinyl chloride (PVC) or urethane, for example. In some embodiments, aslurry distributor constructed in accordance with principles of thepresent disclosure can include a single feed inlet, entry segment, andshaped duct which is in fluid communication with a distribution conduit.

A gypsum slurry distributor constructed in accordance with principles ofthe present disclosure can be used to help provide a wide cross machinedistribution of aqueous calcined gypsum slurry to facilitate thespreading of high viscous/lower WSR gypsum slurries on a web of coversheet material moving over a forming table. The gypsum slurrydistribution system can be used to help control air-slurry phaseseparation, as well.

In accordance with another aspect of the present disclosure, a gypsumslurry mixing and dispensing assembly can include a slurry distributorconstructed in accordance with principles of the present disclosure. Theslurry distributor can be placed in fluid communication with a gypsumslurry mixer adapted to agitate water and calcined gypsum to form anaqueous calcined gypsum slurry. In one embodiment, the slurrydistributor is adapted to receive a first flow and a second flow ofaqueous calcined gypsum slurry from the gypsum slurry mixer anddistribute the first and second flows of aqueous calcined gypsum slurryonto an advancing web.

The slurry distributor can comprise a part of, or act as, a dischargeconduit of a conventional gypsum slurry mixer (e.g., a pin mixer) as isknown in the art. The slurry distributor can be used with components ofa conventional discharge conduit. For example, the slurry distributorcan be used with components of a gate-canister-boot arrangement as knownin the art or of the discharge conduit arrangements described in U.S.Pat. Nos. 6,494,609; 6,874,930; 7,007,914; and 7,296,919.

A slurry distributor constructed in accordance with principles of thepresent disclosure can advantageously be configured as a retrofit in anexisting wallboard manufacturing system. The slurry distributorpreferably can be used to replace a conventional single ormultiple-branch boot used in conventional discharge conduits. Thisgypsum slurry distributor can be retrofitted to an existing slurrydischarge conduit arrangement, such as that shown in U.S. Pat. No.6,874,930 or 7,007,914, for example, as a replacement for the distaldispensing spout or boot. However, in some embodiments, the slurrydistributor may, alternatively, be attached to one or more bootoutlet(s).

Referring to FIGS. 4 and 5, the slurry distributor 220 is similar to theslurry distributor 120 of FIGS. 1-3, except that it is constructed froma substantially rigid material. The interior geometry 207 of the slurrydistributor 220 of FIGS. 4 and 5 is similar to that of the slurrydistributor 120 of FIGS. 1-3, and like reference numerals are used toindicate like structure. The interior geometry 207 of the slurrydistributor 207 is adapted to define a flow path for the gypsum slurrytraveling therethrough which is of the manner of a streamline flow,undergoing reduced or substantially no air-liquid slurry phaseseparation and substantially without undergoing a vortex flow path.

In some embodiments, the slurry distributor 220 can comprise anysuitable substantially rigid material which can include a suitablematerial which can allow the size and shape of the outlet 130 to bemodified using a profile system, for example. For example, a suitablyrigid plastic, such as UHMW plastic, or metal can be used.

Referring to FIG. 4, the slurry distributor 220 has a two-piececonstruction. An upper piece 221 of the slurry distributor 220 includesa recess 227 adapted to receive a profiling system 132 therein. The twopieces 221, 223 can be pivotally movable with respect to each otherabout a hinge 205 at the rear end thereof to allow for ready access toan interior 207 of the slurry distributor 220. Mounting holes 229 areprovided to facilitate the connection of the upper piece 221 and itsmating lower piece 223.

Referring to FIGS. 6-8, another embodiment of a slurry distributor 320constructed in accordance with principles of the present disclosure isshown which is constructed from a rigid material. The slurry distributor320 of FIGS. 6-8 is similar to the slurry distributor 220 of FIGS. 4 and5 except that the first and second feed inlets 324, 325 and the firstand second entry segments 336, 337 of the slurry distributor 320 ofFIGS. 6-8 are disposed at a feed angle δ with respect to thelongitudinal axis or machine direction 50 of about 60° (see FIG. 7).

The slurry distributor 320 has a two-piece construction including anupper piece 321 and its mating lower piece 323. The two pieces 321, 323of the slurry distributor 320 can be secured together using any suitabletechnique, such as by using fasteners through a corresponding number ofmounting holes 329 provided in each piece 321, 323, for example. Theupper piece 321 of the slurry distributor 320 includes a recess 327adapted to receive a profiling system 132 therein. The slurrydistributor 320 of FIGS. 6-8 is similar in other respects to the slurrydistributor 220 of FIGS. 4 and 5.

Referring to FIGS. 9 and 10, the lower piece 323 of the slurrydistributor 320 of FIG. 6 is shown. The lower piece 323 defines a firstportion 331 of the interior geometry 307 of the slurry distributor 320of FIG. 6. The upper piece 323 defines a symmetrical second portion ofthe interior geometry 307 such that when the upper and lower pieces 321,323 are mated together, as shown in FIG. 6, they define the completeinterior geometry 307 of the slurry distributor 320 of FIG. 6.

Referring to FIG. 9, the first and second shaped ducts 341, 343 areadapted to receive the first and second flows of slurry moving in thefirst and second feed flow directions 390, 391 and redirect the slurryflow direction by a change in direction angle α such that the first andsecond flows of slurry are conveyed into the distribution conduit 328moving substantially in the outlet flow direction 392, which is alignedwith the machine direction or longitudinal axis 50.

FIGS. 11 and 12 depict another embodiment of a slurry distributorsupport 300 for use with the slurry distributor 320 of FIG. 6. Theslurry distributor support 300 can include a top and bottom supportplate 301, 302 constructed from a suitably rigid material, such asmetal, for example. The support plates 301, 302 can be secured to thedistributor through any suitable means. In use, the support plates 301,302 can help support the slurry distributor 320 in place over a machineline including a conveyor assembly supporting and transporting a movingcover sheet. The support plates 301, 302 can be mounted to appropriateuprights placed on either side of the conveyor assembly.

FIGS. 13 and 14 depict yet another embodiment of a slurry distributorsupport 310 for use with the slurry distributor 320 of FIG. 6, whichalso includes top and bottom support plates 311, 312. Cutouts 313, 314,318 in the top support plate 311 can make the support 310 lighter thanit would otherwise be and provide access to portions of the slurrydistributor 320, such as those portions accommodating mountingfasteners, for example. The slurry distributor support 310 of FIGS. 13and 14 can be similar in other respects to the slurry distributorsupport 300 of FIGS. 11 and 12.

FIGS. 15-19 illustrate another embodiment of a slurry distributor 420,which is similar to the slurry distributor 320 of FIGS. 6-8, except thatit is constructed from a substantially flexible material. The slurrydistributor 420 of FIGS. 15-19 also includes first and second feedinlets 324, 325 and first and second entry segments 336, 337 which aredisposed at a feed angle θ with respect to the longitudinal axis ormachine direction 50 of about 60° (see FIG. 7). The interior geometry307 of the slurry distributor 420 of FIGS. 15-19 is similar to that ofthe slurry distributor 320 of FIGS. 6-8, and like reference numerals areused to indicate like structure.

FIGS. 17-19 progressively depict the interior geometry of the secondentry segment 337 and the second shaped duct 343 of the slurrydistributor 420 of FIGS. 15 and 16. The cross-sectional areas 411, 412,413, 414 of the outer and inner guide channels 367, 368 can becomeprogressively smaller moving in a second flow direction 397 toward thedistribution outlet 330. The outer guide channel 367 can extendsubstantially along the outer wall 357 of the second shaped duct 343 andalong the sidewall 353 of the distribution conduit 328 to thedistribution outlet 330. The inner guide channel 368 is adjacent theinner wall 358 of the second shaped duct 343 and terminates at the peak375 of the bisected connector segment 339. The slurry distributor 420 ofFIGS. 15-19 is similar in other respects to the slurry distributor 120of FIG. 1 and the slurry distributor 320 of FIG. 6.

Referring to FIGS. 20 and 21, the illustrated embodiment of the slurrydistributor 420 is made from a flexible material, such as PVC orurethane, for example. A slurry distributor support 400 can be providedto help support the slurry distributor 420. The slurry distributorsupport 400 can include a support member, which in the illustratedembodiment is in the form of a bottom support tray 401 filled with asuitable supporting medium 402 which defines a supporting surface 404.The supporting surface 404 is configured to substantially conform to atleast a portion of an exterior of at least one of the feed conduit 322and the distribution conduit 328 to help limit the amount of relativemovement between the slurry distributor 420 and the support tray 401. Insome embodiments, the supporting surface 404 can also help maintain theinterior geometry of the slurry distributor 420 through which a slurrywill flow.

The slurry distributor support 400 can also include a movable supportassembly 405 disposed in spaced relationship to bottom support tray 401.The movable support assembly 405 can be positioned above the slurrydistributor 420 and adapted to be placed in supporting relationship withthe slurry distributor 420 to help maintain the interior geometry 307 ofthe slurry distributor in a desired configuration.

The movable support assembly 405 can include a support frame 407 and aplurality of support segments 415, 416, 417, 418, 419 which are movablysupported by the support frame 407. The support frame 407 can be mountedto at least one of the bottom support tray 401 or a suitably arrangedupright or uprights to retain the support frame 407 in fixedrelationship to the bottom support tray 401.

In embodiments, at least one support segment 415, 416, 417, 418, 419 isindependently movable relative to another support segment 415, 416, 417,418, 419. In the illustrated embodiment, each support segment 415, 416,417, 418, 419 can be independently movable relative to the support frame407 over a predetermined range of travel. In embodiments, each supportsegment 415, 416, 417, 418, 419 is movable over a range of travel suchthat each support segment is in a range of positions over which therespective support segment 415, 416, 417, 418, 419 is in increasingcompressive engagement with a portion of at least one of the feedconduit 322 and the distribution conduit 328.

The position of each support segment 415, 416, 417, 418, 419 can beadjusted to place the support segments 415, 416, 417, 418, 419 incompressive engagement with at least a portion of the slurry distributor420. Each support segment 415, 416, 417, 418, 419 can be independentlyadjusted to place each support segment 415, 416, 417, 418, 419 either infurther compressive engagement with at least a portion of the slurrydistributor 420, thereby locally compressing the interior of the slurrydistributor 420, or in reduced compressive engagement with at least aportion of the slurry distributor 420, thereby allowing the interior ofthe slurry distributor 420 to expand outwardly, such as in response toaqueous gypsum slurry flowing therethrough.

In the illustrated embodiment, each of the support segments 415, 416,417 is movable over a range of travel along the vertical axis 55. Inother embodiments, at least one of the support segments can be movablealong a different line of action.

The movable support assembly 405 includes a clamping mechanism 408associated with each support segment 415, 416, 417, 418, 419. Eachclamping mechanism 408 can be adapted to selectively retain theassociated support segment 415, 416, 417, 418, 419 in a selectedposition relative to the support frame 407.

In the illustrated embodiment, a rod 409 is mounted to each supportsegment 415, 416, 417, 418, 419 and extends upwardly through acorresponding opening in the support frame 407. Each clamping mechanism408 is mounted to the support frame 407 and is associated with one ofthe rods 409 projecting from a respective support segment 415, 416, 417,418, 419. Each clamping mechanism 408 can be adapted to selectivelyretain the associated rod 409 in fixed relationship to the support frame407. The illustrated clamping mechanisms 408 are conventionallever-actuated clamps which encircle the respective rod 409 and allowfor infinitely variable adjustment between the clamping mechanism 408and the associated rod 409.

As one skilled in the art will appreciate, any suitable clampingmechanism 408 can be used in other embodiments. In some embodiments,each associated rod 409 can be moved via a suitable actuator (eitherhydraulic or electric, e.g.) which is controlled via a controller. Theactuator can function as a clamping mechanism by retaining theassociated support segment 415, 416, 417, 418, 419 in a fixed positionrelative to the support frame 407.

Referring to FIG. 21, the support segments 415, 416, 417, 418, 419 caneach include a contacting surface 501, 502, 503, 504, 505 which isconfigured to substantially conform to a surface portion of the desiredgeometric shape of at least one of the feed conduit 322 and thedistribution conduit 328 of the slurry distributor 420. In theillustrated embodiment, a distributor conduit support segment 415 isprovided which includes a contacting surface 501 which conforms to theexterior and interior shape of a portion of the distributor conduit 328over which the distributor conduit support segment 415 is disposed. Apair of shaped duct support segments 416, 417 is provided whichrespectively include a contacting surface 502, 503 which conforms to theexterior and interior shape of a portion of the first and the secondshaped ducts 341, 343, respectively, over which the shaped duct supportsegments 416, 417 are disposed. A pair of entry support segments 418,419 is provided which respectively include a contacting surface 504, 505which conforms to the exterior and interior shape of a portion of thefirst and the second entry segments 336, 337, respectively, over whichthe shaped duct support segments 418, 419 are disposed. The contactingsurfaces 501, 502, 503, 504, 505 are adapted to be placed in contactingrelationship with a selected portion of the slurry distributor 420 tohelp maintain the contacted portion of the slurry distributor 420 inposition to help define the interior geometry 307 of the slurrydistributor 420.

In use, the movable support assembly 405 can be operated to place eachsupport segment 415, 416, 417, 418, 419 independently in a desiredrelationship with the slurry distributor 420. The support segments 415,416, 417, 418, 419 can help maintain the interior geometry 307 of theslurry distributor 420 to promote the flow of slurry therethrough and tohelp ensure the volume defined by the interior geometry 307 issubstantially filled with slurry during use. The location of theparticular contacting surface of a given support segment 415, 416, 417,418, 419 can be adjusted to modify locally the interior geometry of theslurry distributor 420. For example, the distributor conduit supportsegment 415 can be moved along the vertical axis 55 closer to the bottomsupport tray 401 to decrease the height of the distribution conduit 328in an area over which the distributor conduit support segment 415 is.

In other embodiments, the number of support segments can be varied. Instill other embodiments, the size and/or shape of a given supportsegment can be varied.

Any suitable technique for making a slurry distributor constructed inaccordance with principles of the present disclosure can be used. Forexample, in embodiments where the slurry distributor is made from aflexible material, such as PVC or urethane, a multi-piece mold can beused. In some embodiments, the mold piece areas are about 150% or lessthan the area of the molded slurry distributor through which the moldpiece is being pulled during removal, about 125% or less in otherembodiments, about 115% or less in still other embodiments, and about110% or less in yet other embodiments.

Referring to FIGS. 22 and 23, an embodiment of a multi-piece mold 550suitable for use in making the slurry distributor 120 of FIG. 1 from aflexible material, such as PVC or urethane is shown. The illustratedmulti-piece mold 550 includes five mold segments 551, 552, 553, 554,555. The mold segments 551, 552, 553, 554, 555 of the multi-piece mold550 can be made from any suitable material, such as aluminum, forexample.

In the illustrated embodiment, the distributor conduit mold segment 551is configured to define the interior flow geometry of the distributorconduit 128. The first and second shaped duct mold segments 552, 553 areconfigured to define the interior flow geometry of the first and thesecond shaped ducts 141, 143. The first and second entry mold segments554, 555 define the interior flow geometry of the first entry segment136 and the first feed inlet 124 and of the second entry segment 137 andthe second feed inlet 125, respectively. In other embodiments, themulti-piece mold can include a different number of mold segments and/orthe mold segments can have different shapes and/or sizes.

Referring to FIG. 22, connecting bolts 571, 572, 573 can be insertedthrough two or more mold segments to interlock and align the moldsegments 551, 552, 553, 554, 555 such that a substantially continuousexterior surface 580 of the multi-piece mold 550 is defined. In someembodiments, a distal portion 575 of the connecting bolts 571, 572, 573includes an external thread that is configured to threadingly engage oneof the mold segments 551, 552, 553, 554, 555 to interconnect at leasttwo of the mold segments 551, 552, 553, 554, 555. The exterior surface580 of the multi-piece mold 550 is configured to define the interiorgeometry of the molded slurry distributor 120 so that flashing at thejoints is reduced. The connecting bolts 571, 572, 573 can be removed todisassemble the multi-piece mold 550 during removal of the mold 550 fromthe interior of the molded slurry distributor 120.

The assembled multi-piece mold 550 is dipped into a solution of flexiblematerial, such as PVC or urethane, such that the mold 550 is completelysubmersed in the solution. The mold 550 can then be removed from thedipped material. An amount of the solution can adhere to the exteriorsurface 580 of the multi-piece mold 550 which will constitute the moldedslurry distributor 120 once the solution changes to a solid form. Inembodiments, the multi-piece mold 550 can be used in any suitabledipping process to form the molded piece.

By making the mold 550 out of multiple separate aluminum pieces—in theillustrated embodiment, five pieces—that have been designed to fittogether to provide the desired interior flow geometry, the moldsegments 551, 552, 553, 554, 555 can be disengaged from each other andpulled out from the solution once it has begun to set but while it isstill warm. At sufficiently-high temperatures, the flexible material ispliable enough to pull larger calculated areas of the aluminum moldpieces 551, 552, 553, 554, 555 through the smaller calculated areas ofthe molded slurry distributor 120 without tearing it. In someembodiments, the largest mold piece area is up to about 150% of thesmallest area of the molded slurry distributor cavity area through whichthe particular mold piece traverses transversely during the removalprocess, up to about 125% in other embodiments, up to about 115% instill other embodiments, and up to about 110% in yet other embodiments.

Referring to FIG. 24, an embodiment of a multi-piece mold 650 suitablefor use in making the slurry distributor 320 of FIG. 6 from a flexiblematerial, such as PVC or urethane is shown. The illustrated multi-piecemold 650 includes five mold segments 651, 652, 653, 654, 655. The moldsegments 651, 652, 653, 654, 655 of the multi-piece mold 550 can be madefrom any suitable material, such as aluminum, for example. The moldsegments 651, 652, 653, 654, 655 are shown in a disassembled conditionin FIG. 24.

Connecting bolts can be used to removably connect the mold segments 651,652, 653, 654, 655 together to assemble the mold 650 such that asubstantially continuous exterior surface of the multi-piece mold 650 isdefined. The exterior surface of the multi-piece mold 650 defines theinternal flow geometry of the slurry distributor 220 of FIG. 6. The mold650 can be similar in construction to the mold 550 of FIGS. 22 and 23 inthat each piece of the mold 650 of FIG. 24 is constructed such that itsarea is within a predetermined amount of the smallest area of the moldedslurry distributor 220 through which the mold piece must traverse whenit is being removed (e.g., up to about 150% of the smallest area of themolded slurry distributor cavity area through which the particular moldpiece traverses transversely during the removal process in someembodiments, up to about 125% in other embodiments, up to about 115% instill other embodiments, and up to about 110% in yet other embodiments).

Referring to FIGS. 25 and 26, an embodiment of a mold 750 for use inmaking one of the pieces 221, 223 of the two-piece slurry distributor220 of FIG. 4 is shown. Referring to FIG. 25, mounting bore-definingelements 852 can be included to define mounting bores in the piece ofthe two-piece slurry distributor 220 of FIG. 34 being made to facilitateits connection with the other piece.

Referring to FIGS. 25 and 26, the mold 750 includes a mold surface 754projecting from a bottom surface 756 of the mold 750. A boundary wall756 extends along the vertical axis and defines the depth of the mold.The mold surface 754 is disposed within the boundary wall 756. Theboundary wall 756 is configured to allow the volume of a cavity 758defined within the boundary wall to be filled with molten mold materialsuch that the mold surface 754 is immersed. The mold surface 754 isconfigured to be a negative image of the interior flow geometry definedby the particular piece of the two-piece distributor being molded.

In use, the cavity 758 of the mold 750 can be filled with a moltenmaterial such that the mold surface is immersed and the cavity 758 isfilled with molten material. The molten material can be allowed to cooland removed from the mold 750. Another mold can be used to form themating piece of the slurry distributor 220 of FIG. 4.

Referring to FIG. 27, an embodiment of a gypsum slurry mixing anddispensing assembly 810 includes a gypsum slurry mixer 912 in fluidcommunication with a slurry distributor 820 similar to the slurrydistributor 320 shown in FIG. 6. The gypsum slurry mixer 812 is adaptedto agitate water and calcined gypsum to form an aqueous calcined gypsumslurry. Both the water and the calcined gypsum can be supplied to themixer 812 via one or more inlets as is known in the art. Any suitablemixer (e.g., a pin mixer) can be used with the slurry distributor.

The slurry distributor 820 is in fluid communication with the gypsumslurry mixer 812. The slurry distributor 820 includes a first feed inlet824 adapted to receive a first flow of aqueous calcined gypsum slurryfrom the gypsum slurry mixer 812 moving in a first feed direction 890, asecond feed inlet 825 adapted to receive a second flow of aqueouscalcined gypsum slurry from the gypsum slurry mixer 812 moving in asecond feed direction 891, and a distribution outlet 830 in fluidcommunication with both the first and the second feed inlets 824, 825and adapted such that the first and second flows of aqueous calcinedgypsum slurry discharge from the slurry distributor 820 through thedistribution outlet 830 substantially along a machine direction 50.

The slurry distributor 820 includes a feed conduit 822 in fluidcommunication with a distribution conduit 828. The feed conduit includesthe first feed inlet 824 and the second feed inlet 825 disposed inspaced relationship to the first feed inlet 824, which are both disposedat a feed angle θ of about 60° with respect to the machine direction 50.The feed conduit 822 includes structure therein adapted to receive thefirst and second flows of slurry moving in the first and second feedflow direction 890, 891 and redirect the slurry flow direction by achange in direction angle α (see FIG. 9) such that the first and secondflows of slurry are conveyed into the distribution conduit 828 movingsubstantially in the outlet flow direction 892, which is substantiallyaligned with the machine direction 50. The first and second feed inlets824, 825 each has an opening with a cross-sectional area, and the entryportion 852 of the distribution conduit 828 has an opening with across-sectional area which is greater than the sum of thecross-sectional areas of the openings of the first and second feedinlets 824, 825.

The distribution conduit 828 extends generally along the longitudinalaxis or machine direction 50, which is substantially perpendicular to atransverse axis 60. The distribution conduit 828 includes an entryportion 852 and the distribution outlet 830. The entry portion 852 is influid communication with the first and second feed inlets 824, 825 ofthe feed conduit 822 such that the entry portion 852 is adapted toreceive both the first and the second flows of aqueous calcined gypsumslurry therefrom. The distribution outlet 830 is in fluid communicationwith the entry portion 852. The distribution outlet 830 of thedistribution conduit 828 extends a predetermined distance along thetransverse axis 60 to facilitate the discharge of the combined first andsecond flows of aqueous calcined gypsum slurry in the cross-machinedirection or along the transverse axis 60. The slurry distributor 820can be similar in other respects to the slurry distributor 320 of FIG.6.

A delivery conduit 814 is disposed between and in fluid communicationwith the gypsum slurry mixer 812 and the slurry distributor 820. Thedelivery conduit 814 includes a main delivery trunk 815, a firstdelivery branch 817 in fluid communication with the first feed inlet 824of the slurry distributor 820, and a second delivery branch 818 in fluidcommunication with the second feed inlet 825 of the slurry distributor820. The main delivery trunk 815 is in fluid communication with both thefirst and second delivery branches 817, 818. In other embodiments, thefirst and second delivery branches 817, 818 can be in independent fluidcommunication with the gypsum slurry mixer 812.

The delivery conduit 814 can be made from any suitable material and canhave different shapes. In some embodiments, the delivery conduit 814 cancomprise a flexible conduit.

An aqueous foam supply conduit 821 can be in fluid communication with atleast one of the gypsum slurry mixer 812 and the delivery conduit 814.An aqueous foam from a source can be added to the constituent materialsthrough the foam supply conduit 821 at any suitable location downstreamof the mixer 812 and/or in the mixer 812 itself to form a foamed gypsumslurry that is provided to the slurry distributor 220. In theillustrated embodiment, the foam supply conduit 821 is disposeddownstream of the gypsum slurry mixer 812. In the illustratedembodiment, the aqueous foam supply conduit 821 has a manifold-typearrangement for supplying foam to an injection ring or block associatedwith the delivery conduit 814 as described in U.S. Pat. No. 6,874,930,for example.

In other embodiments, one or more foam supply conduits can be providedthat are in fluid communication with the mixer 812. In yet otherembodiments, the aqueous foam supply conduit(s) can be in fluidcommunication with the gypsum slurry mixer alone. As will be appreciatedby those skilled in the art, the means for introducing aqueous foam intothe gypsum slurry in the gypsum slurry mixing and dispensing assembly810, including its relative location in the assembly, can be variedand/or optimized to provide a uniform dispersion of aqueous foam in thegypsum slurry to produce board that is fit for its intended purpose.

Any suitable foaming agent can be used. Preferably, the aqueous foam isproduced in a continuous manner in which a stream of the mix of foamingagent and water is directed to a foam generator, and a stream of theresultant aqueous foam leaves the generator and is directed to and mixedwith the calcined gypsum slurry. Some examples of suitable foamingagents are described in U.S. Pat. Nos. 5,683,635 and 5,643,510, forexample.

When the foamed gypsum slurry sets and is dried, the foam dispersed inthe slurry produces air voids therein which act to lower the overalldensity of the wallboard. The amount of foam and/or amount of air in thefoam can be varied to adjust the dry board density such that theresulting wallboard product is within a desired weight range.

One or more flow-modifying elements 823 can be associated with thedelivery conduit 814 and adapted to control the first and the secondflows of aqueous calcined gypsum slurry from the gypsum slurry mixer812. The flow-modifying element(s) 823 can be used to control anoperating characteristic of the first and second flows of aqueouscalcined gypsum slurry. In the illustrated embodiment of FIG. 27, theflow-modifying element(s) 823 is associated with the main delivery trunk815. Examples of suitable flow-modifying elements include volumerestrictors, pressure reducers, constrictor valves, canisters, etc.,including those described in U.S. Pat. Nos. 6,494,609; 6,874,930;7,007,914; and 7,296,919, for example.

The main delivery trunk 815 can be joined to the first and seconddelivery branches 817, 818 via a suitable Y-shaped flow splitter 819.The flow splitter 819 is disposed between the main delivery trunk 815and the first delivery branch 817 and between the main delivery trunk815 and the second delivery branch 818. In some embodiments, the flowsplitter 819 can be adapted to help split the first and second flows ofgypsum slurry such that they are substantially equal. In otherembodiments, additional components can be added to help regulate thefirst and second flows of slurry.

In use, an aqueous calcined gypsum slurry is discharged from the mixer812. The aqueous calcined gypsum slurry from the mixer 812 is split inthe flow splitter 819 into the first flow of aqueous calcined gypsumslurry and the second flow of aqueous calcined gypsum slurry. Theaqueous calcined gypsum slurry from the mixer 812 can be split such thatthe first and second flows of aqueous calcined gypsum slurry aresubstantially balanced.

Referring to FIG. 28, another embodiment of a gypsum slurry mixing anddispensing assembly 910 is shown. The gypsum slurry mixing anddispensing assembly 910 includes a gypsum slurry mixer 912 in fluidcommunication with a slurry distributor 920. The gypsum slurry mixer 912is adapted to agitate water and calcined gypsum to form an aqueouscalcined gypsum slurry. The slurry distributor 920 can be similar inconstruction and function to the slurry distributor 320 of FIG. 6.

A delivery conduit 914 is disposed between and in fluid communicationwith the gypsum slurry mixer 912 and the slurry distributor 920. Thedelivery conduit 914 includes a main delivery trunk 915, a firstdelivery branch 917 in fluid communication with the first feed inlet 924of the slurry distributor 920, and a second delivery branch 918 in fluidcommunication with the second feed inlet 925 of the slurry distributor920.

The main delivery trunk 915 is disposed between and in fluidcommunication with the gypsum slurry mixer 912 and both the first andthe second delivery branches 917, 918. An aqueous foam supply conduit921 can be in fluid communication with at least one of the gypsum slurrymixer 912 and the delivery conduit 914. In the illustrated embodiment,the aqueous foam supply conduit 921 is associated with the main deliverytrunk 915 of the delivery conduit 914.

The first delivery branch 917 is disposed between and in fluidcommunication with the gypsum slurry mixer 912 and the first feed inlet924 of the slurry distributor 920. At least one first flow-modifyingelement 923 is associated with the first delivery branch 917 and isadapted to control the first flow of aqueous calcined gypsum slurry fromthe gypsum slurry mixer 912.

The second delivery branch 918 is disposed between and in fluidcommunication with the gypsum slurry mixer 912 and the second feed inlet925 of the slurry distributor 920. At least one second flow-modifyingelement 927 is associated with the second delivery branch 918 and isadapted to control the second flow of aqueous calcined gypsum slurryfrom the gypsum slurry mixer 912.

The first and second flow-modifying elements 923, 927 can be operated tocontrol an operating characteristic of the first and second flows ofaqueous calcined gypsum slurry. The first and second flow-modifyingelements 923, 927 can be independently operable. In some embodiments,the first and second flow-modifying elements 923, 927 can be actuated todeliver first and second flows of slurries that alternate between arelatively slower and relatively faster average velocity in opposingfashion such that at a given time the first slurry has an averagevelocity that is faster than that of the second flow of slurry and atanother point in time the first slurry has an average velocity that isslower than that of the second flow of slurry.

As one of ordinary skill in the art will appreciate, one or both of thewebs of cover sheet material can be pre-treated with a very thinrelatively denser layer of gypsum slurry (relative to the gypsum slurrycomprising the core), often referred to as a skim coat in the art,and/or hard edges, if desired. To that end, the mixer 912 includes afirst auxiliary conduit 929 that is adapted to deposit a stream of denseaqueous calcined gypsum slurry that is relatively denser than the firstand second flows of aqueous calcined gypsum slurry delivered to theslurry distributor (i.e., a “face skim coat/hard edge stream”). Thefirst auxiliary conduit 929 can deposit the face skim coat/hard edgestream upon a moving web of cover sheet material upstream of a skim coatroller 931 that is adapted to apply a skim coat layer to the moving webof cover sheet material and to define hard edges at the periphery of themoving web by virtue of the width of the roller 931 being less than thewidth of the moving web as is known in the art. Hard edges can be formedfrom the same dense slurry that forms the thin dense layer by directingportions of the dense slurry around the ends of the roller used to applythe dense layer to the web.

The mixer 912 can also include a second auxiliary conduit 933 adapted todeposit a stream of dense aqueous calcined gypsum slurry that isrelatively denser than the first and second flows of aqueous calcinedgypsum slurry delivered to the slurry distributor (i.e., a “back skimcoat stream”). The second auxiliary conduit 933 can deposit the backskim coat stream upon a second moving web of cover sheet materialupstream (in the direction of movement of the second web) of a skim coatroller 937 that is adapted to apply a skim coat layer to the secondmoving web of cover sheet material as is known in the art (see FIG. 29also).

In other embodiments, separate auxiliary conduits can be connected tothe mixer to deliver one or more separate edge streams to the moving webof cover sheet material. Other suitable equipment (such as auxiliarymixers) can be provided in the auxiliary conduits to help make theslurry therein denser, such as by mechanically breaking up foam in theslurry and/or by chemically breaking down the foam through use of asuitable de-foaming agent.

In yet other embodiments, first and second delivery branches can eachinclude a foam supply conduit therein which are respectively adapted toindependently introduce aqueous foam into the first and second flows ofaqueous calcined gypsum slurry delivered to the slurry distributor. Instill other embodiments, a plurality of mixers can be provided toprovide independent streams of slurry to the first and second feedinlets of a slurry distributor constructed in accordance with principlesof the present disclosure. It will be appreciated that other embodimentsare possible.

The gypsum slurry mixing and dispensing assembly 910 of FIG. 28 can besimilar in other respects to the gypsum slurry mixing and dispensingassembly 810 of FIG. 27. It is further contemplated that other slurrydistributors constructed in accordance with principles of the presentdisclosure can be used in other embodiments of a gypsum slurry mixingand dispensing assembly as described herein.

Referring to FIG. 29, an exemplary embodiment of a wet end 1011 of agypsum wallboard manufacturing line is shown. The wet end 1011 includesa gypsum slurry mixing and dispensing assembly 1010 having a gypsumslurry mixer 1012 in fluid communication with a slurry distributor 1020similar in construction and function to the slurry distributor 320 ofFIG. 6, a hard edge/face skim coat roller 1031 disposed upstream of theslurry distributor 1020 and supported over a forming table 1038 suchthat a first moving web 1039 of cover sheet material is disposedtherebetween, a back skim coat roller 1037 disposed over a supportelement 1041 such that a second moving web 1043 of cover sheet materialis disposed therebetween, and a forming station 1045 adapted to shapethe preform into a desired thickness. The skim coat rollers 1031, 1037,the forming table 1038, the support element 1041, and the formingstation 1045 can all comprise conventional equipment suitable for theirintended purposes as is known in the art. The wet end 1011 can beequipped with other conventional equipment as is known in the art.

In another aspect of the present disclosure, a slurry distributorconstructed in accordance with principles of the present disclosure canbe used in a variety of manufacturing processes. For example, in oneembodiment, a slurry distribution system can be used in a method ofpreparing a gypsum product. A slurry distributor can be used todistribute an aqueous calcined gypsum slurry upon the first advancingweb 1039.

Water and calcined gypsum can be mixed in the mixer 1012 to form thefirst and second flows 1047, 1048 of aqueous calcined gypsum slurry. Insome embodiments, the water and calcined gypsum can be continuouslyadded to the mixer in a water-to-calcined gypsum ratio from about 0.5 toabout 1.3, and in other embodiments of about 0.75 or less.

Gypsum board products are typically formed “face down” such that theadvancing web 1039 serves as the “face” cover sheet of the finishedboard. A face skim coat/hard edge stream 1049 (a layer of denser aqueouscalcined gypsum slurry relative to at least one of the first and secondflows of aqueous calcined gypsum slurry) can be applied to the firstmoving web 1039 upstream of the hard edge/face skim coat roller 1031,relative to the machine direction 1092, to apply a skim coat layer tothe first web 1039 and to define hard edges of the board.

The first flow 1047 and the second flow 1048 of aqueous calcined gypsumslurry are respectively passed through the first feed inlet 1024 and thesecond feed inlet 1025 of the slurry distributor 1020. The first andsecond flows 1047, 1048 of aqueous calcined gypsum slurry are combinedin the slurry distributor 1020. The first and second flows 1047, 1048 ofaqueous calcined gypsum slurry move along a flow path through the slurrydistributor 1020 in the manner of a streamline flow, undergoing minimalor substantially no air-liquid slurry phase separation and substantiallywithout undergoing a vortex flow path.

The first moving web 1039 moves along the longitudinal axis 50. Thefirst flow 1047 of aqueous calcined gypsum slurry passes through thefirst feed inlet 1024, and the second flow 1048 of aqueous calcinedgypsum slurry passes through the second feed inlet 1025. Thedistribution conduit 1028 is positioned such that it extends along thelongitudinal axis 50 which substantially coincides with the machinedirection 1092 along which the first web 1039 of cover sheet materialmoves. Preferably, the central midpoint of the distribution outlet 1030(taken along the transverse axis/cross-machine direction 60)substantially coincides with the central midpoint of the first movingcover sheet 1039. The first and second flows 1047, 1048 of aqueouscalcined gypsum slurry combine in the slurry distributor 1020 such thatthe combined first and second flows 1051 of aqueous calcined gypsumslurry pass through the distribution outlet 1030 in a distributiondirection 1093 generally along the machine direction 1092.

In some embodiments, the distribution conduit 1028 is positioned suchthat it is substantially parallel to the plane defines by thelongitudinal axis 50 and the transverse axis 60 of the first web 1039moving along the forming table. In other embodiments, the entry portionof the distribution conduit can be disposed vertically lower or higherthan the distribution outlet 1030 relative to the first web 1039.

The combined first and second flows 1051 of aqueous calcined gypsumslurry are discharged from the slurry distributor 1020 upon the firstmoving web 1039. The face skim coat/hard edge stream 1049 can bedeposited from the mixer 1012 at a point upstream, relative to thedirection of movement of the first moving web 1039 in the machinedirection 1092, of where the first and second flows 1047, 1048 ofaqueous calcined gypsum slurry are discharged from the slurrydistributor 1020 upon the first moving web 1039. The combined first andsecond flows 1047, 1048 of aqueous calcined gypsum slurry can bedischarged from the slurry distributor with a reduced momentum per unitwidth along the cross-machine direction relative to a conventional bootdesign to help prevent “washout” of the face skim coat/hard edge stream1049 deposited on the first moving web 1039 (i.e., the situation where aportion of the deposited skim coat layer is displaced from its positionupon the moving web 339 in response to the impact of the slurry beingdeposited upon it).

The first and second flows 1047, 1048 of aqueous calcined gypsum slurryrespectively passed through the first and second feed inlets 1024, 1025of the slurry distributor 1020 can be selectively controlled with atleast one flow-modifying element 1023. For example, in some embodiments,the first and second flows 1047, 1048 of aqueous calcined gypsum slurryare selectively controlled such that the average velocity of the firstflow 1047 of aqueous calcined gypsum slurry passing through the firstfeed inlet 1024 and the average velocity of the second flow 1048 ofaqueous calcined gypsum slurry passing through the second feed inlet1025 are substantially the same.

In embodiments, the first flow 1047 of aqueous calcined gypsum slurry ispassed at an average first feed velocity through the first feed inlet1024 of the slurry distributor 1020. The second flow 1048 of aqueouscalcined gypsum slurry is passed at an average second feed velocitythrough the second feed inlet 1025 of the slurry distributor 1020. Thesecond feed inlet 1025 is in spaced relationship to the first feed inlet1024. The first and second flows 1051 of aqueous calcined gypsum slurryare combined in the slurry distributor 1020. The combined first andsecond flows 1051 of aqueous calcined gypsum slurry are discharged at anaverage discharge velocity from a distribution outlet 1030 of the slurrydistributor 1020 upon the web 1039 of cover sheet material moving alonga machine direction 1092. The average discharge velocity is less thanthe average first feed velocity and the average second feed velocity.

In some embodiments, the average discharge velocity is less than about90% of the average first feed velocity and the average second feedvelocity. In some embodiments, the average discharge velocity is lessthan about 80% of the average first feed velocity and the average secondfeed velocity.

The combined first and second flows 1051 of aqueous calcined gypsumslurry are discharged from the slurry distributor 1020 through thedistribution outlet 1030. The opening of the distribution outlet 1030has a width extending along the transverse axis 60 and sized such thatthe ratio of the width of the first moving web 1039 of cover sheetmaterial to the width of the opening of the distribution outlet 1030 iswithin a range including and between about 1:1 and about 6:1. In someembodiments, the ratio of the average velocity of the combined first andsecond flows 1051 of aqueous calcined gypsum slurry discharging from theslurry distributor 1020 to the velocity of the moving web 1039 of coversheet material moving along the machine direction 1092 can be about 2:1or less in some embodiments, and from about 1:1 to about 2:1 in otherembodiments.

The combined first and second flows 1051 of aqueous calcined gypsumslurry discharging from the slurry distributor 1020 form a spreadpattern upon the moving web 1039. At least one of the size and shape ofthe distribution outlet 1030 can be adjusted, which in turn can changethe spread pattern.

Thus, slurry is fed into both feed inlets 1024, 1025 of the feed conduit1022 and then exits through the distribution outlet 1030 with anadjustable gap. A converging portion 1082 can provide a slight increasein the slurry velocity so as to reduce unwanted exit effects and therebyfurther improve flow stability at the free surface. Side-to-side flowvariation and/or any local variations can be reduced by performingcross-machine (CD) profiling control at the discharge outlet 1030 usingthe profiling system. This distribution system can help preventair-liquid slurry separation in the slurry resulting in a more uniformand consistent material delivered to the forming table 1038.

A back skim coat stream 1053 (a layer of denser aqueous calcined gypsumslurry relative to at least one of the first and second flows 1047, 1048of aqueous calcined gypsum slurry) can be applied to the second movingweb 1043. The back skim coat stream 1053 can be deposited from the mixer1012 at a point upstream, relative to the direction of movement of thesecond moving web 1043, of the back skim coat roller 1037.

In other embodiments, the average velocity of the first and second flows1047, 1048 of aqueous calcined gypsum slurry are varied. In someembodiments, the slurry velocities at the feed inlets 1024, 1025 of thefeed conduit 1022 can oscillate periodically between relatively higherand lower average velocities (at one point in time one inlet has ahigher velocity than the other inlet, and then at a predetermined pointin time vice versa) to help reduce the chance of buildup within thegeometry itself.

In embodiments, the first flow 1047 of aqueous calcined gypsum slurrypassing through the first feed inlet 1024 has a shear rate that is lowerthan the shear rate of the combined first and second flows 1051discharging from the distribution outlet 1030, and the second flow 1048of aqueous calcined gypsum slurry passing through the second feed inlet1025 has a shear rate that is lower than the shear rate of the combinedfirst and second flows 1051 discharging from the distribution outlet1030. In embodiments, the shear rate of the combined first and secondflows 1051 discharging from the distribution outlet 1030 can be greaterthan about 150% of the shear rate of the first flow 1047 of aqueouscalcined gypsum slurry passing through the first feed inlet 1024 and/orthe second flow 1048 of aqueous calcined gypsum slurry passing throughthe second feed inlet 1025, greater than about 175% in still otherembodiments, and about double or greater in yet other embodiments. Itshould be understood that the viscosity of the first and second flows1047, 1048 of aqueous calcined gypsum slurry and the combined first andsecond flows 1051 can be inversely related to the shear rate present ata given location such that as the shear rate goes up, the viscositydecreases.

In embodiments, the first flow 1047 of aqueous calcined gypsum slurrypassing through the first feed inlet 1024 has a shear stress that islower than the shear stress of the combined first and second flows 1051discharging from the distribution outlet 1030, and the second flow 1048of aqueous calcined gypsum slurry passing through the second feed inlet1025 has a shear stress that is lower than the shear stress of thecombined first and second flows 1051 discharging from the distributionoutlet 1030. In embodiments, the shear stress of the combined first andsecond flows 1051 discharging from the distribution outlet 1030 can begreater than about 110% of the shear rate of the first flow 1047 ofaqueous calcined gypsum slurry passing through the first feed inlet 1024and/or the second flow 1048 of aqueous calcined gypsum slurry passingthrough the second feed inlet 1025.

In embodiments, the first flow 1047 of aqueous calcined gypsum slurrypassing through the first feed inlet 1024 has a Reynolds number that ishigher than the Reynolds number of the combined first and second flows1051 discharging from the distribution outlet 1030, and the second flow1048 of aqueous calcined gypsum slurry passing through the second feedinlet 1025 has a Reynolds number that is higher than the Reynolds numberof the combined first and second flows 1051 discharging from thedistribution outlet 1030. In embodiments, the Reynolds number of thecombined first and second flows 1051 discharging from the distributionoutlet 1030 can be less than about 90% of the Reynolds number of thefirst flow 1047 of aqueous calcined gypsum slurry passing through thefirst feed inlet 1024 and/or the second flow 1048 of aqueous calcinedgypsum slurry passing through the second feed inlet 1025, less thanabout 80% in still other embodiments, and less than about 70% in stillother embodiments.

Referring to FIG. 30, an embodiment of a Y-shaped flow splitter 1100suitable for use in a gypsum slurry mixing and dispensing assemblyconstructed in accordance with principles of the present disclosure isshown. The flow splitter 1100 can be placed in fluid communication witha gypsum slurry mixer and a slurry distributor such that the flowsplitter 1100 receives a single flow of aqueous calcined gypsum slurryfrom the mixer and discharges two separate flows of aqueous calcinedgypsum slurry therefrom to the first and second feed inlets of theslurry distributor. One or more flow-modifying elements can be disposedbetween the mixer and the flow splitter 1100 and/or between one or bothof the delivery branches leading between the splitter 1100 and theassociated slurry distributor.

The flow splitter 1100 has a substantially circular inlet 1102 disposedin a main branch 1103 adapted to receive a single flow of slurry and apair of substantially circular outlets 1104, 1106 disposed respectivelyin first and second outlet branches 1105, 1107 that allow two flows ofslurry to discharge from the splitter 1100. The cross-sectional areas ofthe openings of the inlet 1102 and the outlets 1104, 1106 can varydepending on the desired flow velocity. In embodiments where thecross-sectional areas of the openings of outlet 1104, 1106 are eachsubstantially equal to cross-sectional area of the opening of the inlet1102, the flow velocity of the slurry discharging from each outlet 1104,1106 can be reduced to about 50% of the velocity of the single flow ofslurry entering the inlet 1102 where the volumetric flow rate throughthe inlet 1102 and both outlets 1104, 1106 is substantially the same.

In some embodiments, the diameter of the outlets 1104, 1106 can be madesmaller than the diameter of the inlet 1102 in order to maintain arelatively high flow velocity throughout the splitter 1100. Inembodiments where the cross-sectional areas of the openings of theoutlets 1104, 1106 are each smaller than the cross-sectional area of theopening of the inlet 1102, the flow velocity can be maintained in theoutlets 1104, 1106 or at least reduced to a lesser extent than if theoutlets 1104, 1106 and the inlet 1102 all have substantially equalcross-sectional areas. For example, in some embodiments, the flowsplitter 1100 has the inlet 1102 has an inner diameter (ID₁) of about 3inches, and each outlet 1104, 1106 has an ID₂ of about 2.5 inches(though other inlet and outlet diameters can be used in otherembodiments). In an embodiment with these dimensions at a line speed of350 fpm, the smaller diameter of the outlets 1104, 1106 causes the flowvelocity in each outlet to be reduced by about 28% of the flow velocityof the single flow of slurry at the inlet 1102.

The flow splitter 1100 can includes a central contoured portion 1114 anda junction 1120 between the first and second outlet branches 1105, 1107.The central contoured portion 1114 creates a restriction 1108 in thecentral interior region of the flow splitter 1100 upstream of thejunction 1120 that helps promote flow to the outer edges 1110, 1112 ofthe splitter to reduce the occurrence of slurry buildup at the junction1120. The shape of the central contoured portion 1114 results in guidechannels 1111, 1113 adjacent the outer edges 1110, 1112 of the flowsplitter 1100. The restriction 1108 in the central contoured portion1114 has a smaller height H₂ than the height H₃ of the guide channels1111, 1113. The guide channels 1111, 1113 have a cross-sectional areathat is larger than the cross-sectional area of the central restriction1108. As a result, the flowing slurry encounters less flow resistancethrough the guide channels 1111, 1113 than through the centralrestriction 1108, and flow is directed toward the outer edges of thesplitter junction 1120.

The junction 1120 establishes the openings to the first and secondoutlet branches 1105, 1107. The junction 1120 is made up of a planarwall surface 1123 that is substantially perpendicular to an inlet flowdirection 1125.

Referring to FIG. 32, in some embodiments, an automatic device 1150 forsqueezing the splitter 1100 at adjustable and regular time intervals canbe provided to prevent solids building up inside the splitter 1100. Insome embodiments, the squeezing apparatus 1150 can include a pair ofplates 1152, 1154 disposed on opposing sides 1142, 1143 of the centralcontoured portion 1114. The plates 1152, 1154 are movable relative toeach other by a suitable actuator 1160. The actuator 1160 can beoperated either automatically or selectively to move the plates 1152,1154 together relative to each other to apply a compressive force uponthe splitter 1100 at the central contoured portion 1114 and the junction1120.

When the squeezing apparatus 1150 squeezes the flow splitter, thesqueezing action applies compressive force to the flow splitter 1100,which flexes inwardly in response. This compressive force can helpprevent buildup of solids inside the splitter 1100 which may disrupt thesubstantially equally split flow to the slurry distribution through theoutlets 1104, 1106. In some embodiments, the squeezing apparatus 1150 isdesigned to automatically pulse through the use of a programmablecontroller operably arranged with the actuators. The time duration ofthe application of the compressive force by the squeezing apparatus 1150and/or the interval between pulses can be adjusted. Furthermore, thestroke length that the plates 1152, 1154 travel with respect to eachother in a compressive direction can be adjusted.

Embodiments of a slurry distributor, a gypsum slurry mixing anddispensing assembly, and methods of using the same are provided hereinwhich can provide many enhanced process features helpful inmanufacturing gypsum wallboard in a commercial setting. A slurrydistributor constructed in accordance with principles of the presentdisclosure can facilitate the spreading of aqueous calcined gypsumslurry upon a moving web of cover sheet material as it advances past amixer at the wet end of the manufacturing line toward a forming station.

A gypsum slurry mixing and dispensing assembly constructed in accordancewith principles of the present disclosure can split a flow of aqueouscalcined gypsum slurry from a mixer into two separate flows of aqueouscalcined gypsum slurry which can be recombined downstream in a slurrydistributor constructed in accordance with principles of the presentdisclosure to provide a desired spreading pattern. The design of thedual inlet configuration and the distribution outlet can allow for widerspreading of more viscous slurry in the cross-machine direction over themoving web of cover sheet material. The slurry distributor can beadapted such that the two separate flows of aqueous calcined gypsumslurry enter a slurry distributor along feed inlet directions whichinclude a cross-machine direction component, are re-directed inside theslurry distributor such that the two flows of slurry are moving insubstantially a machine direction, and are recombined in the distributorin a way to enhance the cross-direction uniformity of the combined flowsof aqueous calcined gypsum slurry being discharged from the distributionoutlet of the slurry distributor to help reduce mass flow variation overtime along the transverse axis or cross machine direction. Introducingthe first and second flows of aqueous calcined gypsum slurry in firstand second feed directions that include a cross-machine directionalcomponent can help the re-combined flows of slurry discharge from theslurry distributor with a reduced momentum and/or energy.

The interior flow cavity of the slurry distributor can be configuredsuch that each of the two flows of slurry move through the slurrydistributor in a streamline flow. The interior flow cavity of the slurrydistributor can be configured such that each of the two flows of slurrymove through the slurry distributor with minimal or substantially noair-liquid slurry phase separation. The interior flow cavity of theslurry distributor can be configured such that each of the two flows ofslurry move through the slurry distributor substantially withoutundergoing a vortex flow path.

A gypsum slurry mixing and dispensing assembly constructed in accordancewith principles of the present disclosure can include flow geometryupstream of the distribution outlet of the slurry distributor to reducethe slurry velocity in one or multiple steps. For example, a flowsplitter can be provided between the mixer and the slurry distributor toreduce the slurry velocity entering the slurry distributor. As anotherexample, the flow geometry in the gypsum slurry mixing and dispensingassembly can include areas of expansion upstream and within the slurrydistributor to slow down the slurry so it is manageable when it isdischarged from the distribution outlet of the slurry distributor.

The geometry of the distribution outlet can also help control thedischarge velocity and momentum of the slurry as it is being dischargedfrom the slurry distributor upon the moving web of cover sheet material.The flow geometry of the slurry distributor can be adapted such that theslurry discharging from the distribution outlet is maintained insubstantially a two-dimensional flow pattern with a relatively smallheight in comparison to the wider outlet in the cross-machine directionto help improve stability and uniformity.

The relatively wide discharge outlet yields a momentum per unit width ofthe slurry being discharged from the distribution outlet that is lowerthan the momentum per unit width of a slurry discharged from aconventional boot under similar operating conditions. The reducedmomentum per unit width can help prevent washout of a skim coat of adense layer applied to the web of cover sheet material upstream from thelocation where the slurry is discharged from the slurry distributor uponthe web.

In the situation where a conventional boot outlet is 6 inches wide and 2inches thick is used, the average velocity of the outlet for a highvolume product can be about 761 ft/min. In embodiments where the slurrydistributor constructed in accordance with principles of the presentdisclosure includes a distribution outlet having an opening that is 24inches wide and 0.75 inches thick, the average velocity can be about 550ft/min. The mass flow rate is the same for both devices at 3,437 lb/min.The momentum of the slurry (mass flow rate*average velocity) for bothcases would be ˜2,618,000 and 1,891,000 lb·ft/min² for the conventionalboot and the slurry distributor, respectively. Dividing the respectivecalculated momentum by the widths of the conventional boot outlet andthe slurry distributor outlet, the momentum per unit width of the slurrydischarging from the convention boot is 402,736 (lb·ft/min²)/(inchacross boot width), and the momentum per unit width of the slurrydischarging from the slurry distributor constructed in accordance withprinciples of the present disclosure is 78,776 (lb·ft/min²)/(inch acrossslurry distributor width). In this case, the slurry discharging from theslurry distributor has about 20% of the momentum per unit width comparedto the conventional boot.

A slurry distributor constructed in accordance with principles of thepresent disclosure can achieve a desired spreading pattern while usingan aqueous calcined gypsum slurry over a broad range of water-stuccoratios, including a relatively low WSR or a more conventional WSR, suchas, a water-to-calcined gypsum ratio from about 0.4 to about 1.2, forexample, below 0.75 in some embodiments, and between about 0.4 and about0.8 in other embodiments. Embodiments of a slurry distributorconstructed in accordance with principles of the present disclosure caninclude internal flow geometry adapted to generate controlled sheareffects upon the first and second flows of aqueous calcined gypsumslurry as the first and second flows advance from the first and secondfeed inlets through the slurry distributor toward the distributionoutlet. The application of controlled shear in the slurry distributorcan selectively reduce the viscosity of the slurry as a result of beingsubjected to such shear. Under the effects of controlled shear in theslurry distributor, slurry having a lower water-stucco ratio can bedistributed from the slurry distributor with a spread pattern in thecross-machine direction comparable to slurries having a conventionalWSR.

The interior flow geometry of the slurry distributor can be adapted tofurther accommodate slurries of various water-stucco ratios to provideincrease flow adjacent the boundary wall regions of the interiorgeometry of the slurry distributor. By including flow geometry featuresin the slurry distributor adapted to increase the degree of flow aroundthe boundary wall layers, the tendency of slurry to re-circulate in theslurry distributor and/or stop flowing and set therein is reduced.Accordingly, the build up of set slurry in the slurry distributor can bereduced as a result.

A slurry distributor constructed in accordance with principles of thepresent disclosure can include a profile system mounted adjacent thedistribution outlet to alter a cross machine velocity component of thecombined flows of slurry discharging from the distribution outlet toselectively control the spread angle and spread width of the slurry inthe cross machine direction on the substrate moving down themanufacturing line toward the forming station. The profile system canhelp the slurry discharged from the distribution outlet achieve adesired spread pattern while being less sensitive to slurry viscosityand WSR. The profile system can be used to change the flow dynamics ofthe slurry discharging from the distribution outlet of the slurrydistributor to guide slurry flow such that the slurry has more uniformvelocity in the cross-machine direction. Using the profile system canalso help a gypsum slurry mixing and dispensing assembly constructed inaccordance with principles of the present disclosure be used in a gypsumwallboard manufacturing setting to produce wallboard of different typesand volumes.

EXAMPLES

Referring to FIG. 33, in these Examples the geometry and flowcharacteristics of a slurry distributor constructed in accordance withprinciples of the present disclosure were evaluated. A top plan view ofa half portion 1205 of a slurry distributor is shown in FIG. 33. Thehalf portion 1205 of the slurry distributor includes a half portion 1207of a feed conduit 320 and a half portion 1209 of a distribution conduit328. The half portion 1207 of the feed conduit 322 includes a secondfeed inlet 325 defining a second opening 335, a second entry segment337, and a half portion 1211 of a bifurcated connector segment 339. Thehalf portion 1209 of the distribution conduit 328 includes a halfportion 1214 of an entry portion 352 of the distribution conduit 328 anda half portion 1217 of a distribution outlet 330.

It should be understood that another half portion of a slurrydistributor, which is a mirror image of the half portion 1205 of FIG.33, can be integrally joined and aligned with the half portion 1205 ofFIG. 33 at a transverse central midpoint 387 of the distribution outlet330 to form a slurry distributor which is substantially similar to theslurry distributor 420 of FIG. 15. Accordingly, the geometry and flowcharacteristics described below are equally applicable to the mirrorimage half portion of the slurry distributor as well.

Example 1

In this Example and referring to FIG. 33, the particular geometry of thehalf portion 1205 of the slurry distributor was evaluated at sixteendifferent locations L₁₋₁₆ between a first location L₁ at the second feedinlet 325 and a sixteenth location L₁₆ at a half portion 1207 of thedistribution outlet 330. Each location L₁₋₁₆ represents across-sectional slice of the half portion 1205 of the slurry distributoras indicated by the corresponding line. A flow line 1212 along thegeometric center of each cross-sectional slice was used to determine thedistance between adjacent locations L₁₋₁₆. The eleventh location L₁₁corresponds to the half portion 1214 of the entry portion 352 of thedistribution conduit 328 which corresponds to an opening 342 of a secondfeed outlet 345 of the half portion 1207 of the feed conduit 320.Accordingly, the first through the tenth locations L₁₋₁₀ are taken inthe half portion 1207 of the feed conduit 320, and the eleventh throughthe sixteenth locations are taken in the half portion 1209 of thedistribution conduit 328.

For each location L₁₋₁₆, the following geometric values of weredetermined: the distance along the flow line 1212 between the secondfeed inlet 325 and the particular location L₁₋₁₆; the cross-sectionalarea of the opening at the location L₁₋₁₆; the perimeter of the locationL₁₋₁₆; and the hydraulic diameter of the location L₁₋₁₆. The hydraulicdiameter was calculated using the following formula:D _(hyd)=4×A/P  (Eq. 1)

-   -   where D_(hyd) is the hydraulic diameter,    -   A is the area of the particular location L₁₋₁₆, and    -   P is the perimeter of the particular location L₁₋₁₆.        Using the inlet conditions, the dimensionless values for each        location L₁₋₁₆ can be determined to describe the interior flow        geometry, as shown in Table 1. Curve-fit equations were used to        describe the dimensionless geometry of the half portion 1205 of        the slurry distributor in FIG. 34, which shows the dimensionless        distance from inlet versus the dimensionless area and the        hydraulic diameter.

The analysis of the dimensionless values for each location L₁₋₁₆ showsthat the cross sectional flow area increases from the first location L₁at the second feed inlet 325 to the eleventh location L₁₁ at the halfportion 1214 of the entry portion 352 (also the opening 342 of thesecond feed outlet 345). In the exemplary embodiment, thecross-sectional flow area at the half portion 1214 of the entry portion352 is about ⅓ larger than the cross-sectional flow area at the secondfeed inlet 325. Between the first location L₁ and the eleventh locationL₁₁, the cross-sectional flow area of the second entry segment 337 andthe second shaped duct 339 varies from location to location L₁₋₁₁. Inthis region, at least two adjacent locations L₆, L₇ are configured suchthat the location L₇ located further from the second feed inlet 325 hasa cross sectional flow area that is smaller than the adjacent locationL₆ that is closer to the second feed inlet 325.

Between the first location L₁ and the eleventh location L₁₁, in the halfportion 1207 of the feed conduit 322 there is an area of expansion(e.g., L₄₋₆) having a cross-sectional flow area that is greater than across-sectional flow area of an adjacent area (e.g., L₃) upstream fromthe area of expansion in a direction from the second inlet 335 towardthe half portion 1217 of the distribution outlet 330. The second entrysegment 337 and the second shaped duct 341 have a cross section thatvaries along the direction of flow 1212 to help distribute the secondflow of slurry moving therethrough.

The cross sectional area decreases from the eleventh location L₁₁ at thehalf portion 1214 of the entry portion 352 of the distribution conduit328 to the sixteenth location L₁₆ at the half portion 1217 of thedistribution outlet 330 of the distribution conduit 328. In theexemplary embodiment, the cross-sectional flow area of the half portion1214 of an entry portion 352 is about 95% of that of the half portion1217 of the distribution outlet 330.

The cross-sectional flow area at the first location L₁ at the secondfeed inlet 325 is smaller than the cross-sectional flow area at thesixteenth location L₁₆ at the half portion 1217 of the distributionoutlet 330 of the distribution conduit 328. In the exemplary embodiment,the cross-sectional flow area at the half portion 1217 of thedistribution outlet 330 of the distribution conduit 328 is about ¼larger than the cross-sectional flow area at the second feed inlet 325.

The hydraulic diameter decreases from the first location L₁ at thesecond feed inlet 325 to the eleventh location L₁₁ at the half portion1214 of the entry portion 352 of the distribution conduit 328. In theexemplary embodiment, the hydraulic diameter at the half portion 1214 ofthe entry portion 352 of the distribution conduit 328 is about ½ thehydraulic diameter at the second feed inlet 325.

The hydraulic diameter decreases from the eleventh location L₁₁ at thehalf portion 1214 of an entry portion 352 of the distribution conduit328 to the sixteenth location L₁₆ at the half portion 1217 of thedistribution outlet 330 of the distribution conduit 328. In theexemplary embodiment, the hydraulic diameter of the half portion 1217 ofthe distribution outlet 330 of the distribution conduit 328 is about 95%of that of the half portion 1214 of the entry portion 352 of thedistribution conduit 328.

The hydraulic diameter at the first location L₁ at the second inlet 325is larger than the hydraulic diameter at the sixteenth location L₁₆ atthe half portion 1217 of the distribution outlet 330 of the distributionconduit 328. In the exemplary embodiment, the hydraulic diameter at thehalf portion 1217 of the distribution outlet 330 of the distributionconduit 328 is less than about half of that of the second feed inlet325.

TABLE I GEOMETRY Dimensionless Distance Hydraulic Location From InletArea Perimeter Dia. L1 0.00 1.00 1.00 1.00 L2 0.07 1.00 1.00 1.00 L30.14 0.91 0.98 0.93 L4 0.20 1.01 1.07 0.94 L5 0.27 1.18 1.24 0.95 L60.34 1.25 1.45 0.87 L7 0.41 1.16 1.68 0.69 L8 0.47 1.13 1.93 0.59 L90.54 1.23 2.20 0.56 L10 0.61 1.35 2.47 0.55 L11 0.68 1.33 2.73 0.49 L120.75 1.28 2.70 0.47 L13 0.81 1.27 2.68 0.48 L14 0.88 1.26 2.67 0.47 L150.95 1.26 2.67 0.47 L16 1.00 1.26 2.67 0.47

Example 2

In this Example, the half portion 1205 of the slurry distributor of FIG.33 was used to model the flow of gypsum slurry therethrough underdifferent flow conditions. For all flow conditions, the density (ρ) ofthe aqueous gypsum slurry was set at 1,000 kg/m³. Aqueous gypsum slurryis a shear-thinning material such that as shear is applied to it, itsviscosity can decrease. The viscosity (μ) Pa·s of the gypsum slurry wascalculated using the Power Law Fluid Model which has the followingequation:μ=K{dot over (γ)} ^(n-1)  (Eq. 2)

-   -   where,    -   K is a constant,    -   {dot over (γ)} is the shear rate, and    -   n is a constant equal to 0.133 in this case.

In a first flow condition, the gypsum slurry has a viscosity K factor of50 in the Power Law model and enters the second feed inlet 325 at 2.5m/s. A computational fluid dynamics technique with a finite volumemethod was used to determine flow characteristics in the distributor. Ateach location L₁₋₁₆, the following flow characteristics were determined:area-weighted average velocity (U), area-weighted average shear rate({dot over (γ)}), viscosity calculated using the Power Law Model (Eq.2), shear stress, and Reynolds Number (Re).

The shear stress was calculated using the following equation:Shear stress=μ×{dot over (γ)}  (Eq. 3)

-   -   where    -   μ is the viscosity calculated using the Power Law Model (Eq. 2),        and    -   {dot over (γ)} is the shear rate.

The Reynolds Number was calculated using the following equation:Re==ρ×U×D _(hyd)/μ  (Eq. 4)

-   -   where    -   ρ is the density of the gypsum slurry,    -   U is the area-weighted average velocity,    -   D_(hyd) is the hydraulic diameter, and    -   μ is the viscosity calculated using the Power Law Model (Eq. 2).

In a second flow condition case, the feed velocity of the gypsum slurryinto the second feed inlet 325 was increased to 3.55 m/s. All otherconditions were the same as in the first flow condition of this Example.The dimensional values for the mentioned flow characteristics at eachlocation L₁₋₁₆ for both the first flow condition where the inletvelocity is 2.5 m/s and the second flow condition where the inletvelocity is 3.55 m/s were modeled. Using the inlet conditions,dimensionless values of the flow characteristics for each location L₁₋₁₆were determined, as shown in Table II.

For both flow conditions where K was set equal to 50, the averagevelocity was reduced from the first location L₁ at the second feed inlet325 to the sixteenth location L₁₆ at the half portion 1217 of thedistribution outlet 330 of the distribution conduit 328. In theillustrated embodiment, the average velocity was reduced by about ⅕.

For both flow conditions, the shear rate increased from the firstlocation L₁ at the second feed inlet 325 to the sixteenth location L₁₆at the half portion 1217 of the distribution outlet 330 of thedistribution conduit 328. In the illustrated embodiment, the shear rateapproximately doubled from the first location L₁ at the second feedinlet 325 to the sixteenth location L₁₆ at the half portion 1217 of thedistribution outlet 330 of the distribution conduit 328, as shown inFIG. 36.

For both flow conditions, the calculated viscosity was reduced from thefirst location L₁ at the second feed inlet 325 to the sixteenth locationL₁₆ at the half portion 1217 of the distribution outlet 330 of thedistribution conduit 328. In the illustrated embodiment, the calculatedviscosity was reduced from the first location L₁ at the second feedinlet 325 to the sixteenth location L₁₆ at the half portion 1217 of thedistribution outlet 330 of the distribution conduit 328 by about half,as illustrated in FIG. 37.

For both flow conditions in FIG. 38, the shear stress increased from thefirst location L₁ at the second feed inlet 325 to the sixteenth locationL₁₆ at the half portion 1217 of the distribution outlet 330 of thedistribution conduit 328. In the illustrated embodiment, the shearstress increased by about 10% from the first location L₁ at the secondfeed inlet 325 to the sixteenth location L₁₆ at the half portion 1217 ofthe distribution outlet 330 of the distribution conduit 328.

For both flow conditions, the Reynolds number in FIG. 39 was reducedfrom the first location L₁ at the second feed inlet 325 to the sixteenthlocation L₁₆ at the half portion 1217 of the distribution outlet 330 ofthe distribution conduit 328. In the illustrated embodiment, theReynolds number was reduced from the first location L₁ at the secondfeed inlet 325 to the sixteenth location L₁₆ at the half portion 1217 ofthe distribution outlet 330 of the distribution conduit 328 by about ⅓.For both flow conditions, the Reynolds number at the sixteenth locationL₁₆ at the half portion 1217 of the distribution outlet 330 of thedistribution conduit 328 is in the laminar region.

TABLE II DIMENSIONLESS FLOW CHARACTERISTICS (K = 50) Inlet Velocity =2.50 m/s Inlet Velocity = 3.55 m/s Shear Calc Shear Shear Calc ShearLocation Velocity Rate Visc. Stress Re Velocity Rate Visc. Stress Re L11.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 L2 1.00 1.18 0.87 1.021.15 1.00 1.20 0.85 1.03 1.17 L3 1.10 1.36 0.77 1.04 1.33 1.10 1.40 0.751.05 1.36 L4 1.00 1.30 0.80 1.04 1.18 0.99 1.32 0.79 1.04 1.19 L5 0.861.19 0.86 1.02 0.96 0.86 1.22 0.84 1.03 0.98 L6 0.83 1.23 0.83 1.03 0.860.83 1.28 0.81 1.03 0.89 L7 0.90 1.65 0.65 1.07 0.96 0.90 1.73 0.62 1.080.99 L8 0.90 1.73 0.62 1.08 0.85 0.90 1.80 0.60 1.08 0.88 L9 0.82 1.670.64 1.07 0.72 0.82 1.74 0.62 1.08 0.74 L10 0.77 1.63 0.65 1.07 0.640.77 1.73 0.62 1.08 0.68 L11 0.76 1.83 0.59 1.08 0.62 0.76 1.93 0.571.09 0.65 L12 0.78 1.84 0.59 1.08 0.63 0.78 1.92 0.57 1.09 0.65 L13 0.781.88 0.58 1.09 0.64 0.78 1.93 0.57 1.09 0.65 L14 0.78 1.88 0.58 1.090.64 0.78 1.95 0.56 1.09 0.66 L15 0.78 1.85 0.59 1.09 0.63 0.78 1.920.57 1.09 0.65 L16 0.79 1.89 0.58 1.09 0.65 0.79 1.98 0.55 1.09 0.67

Example 3

In this Example, the half portion 1205 of the slurry distributor of FIG.33 was used to model the flow of gypsum slurry therethrough under flowconditions similar to those in Example 2 except that the value for thecoefficient K in the Power Law Model (Eq. 2) was set at 100. The flowconditions were similar to those in Example 2 in other respects.

Again, the flow characteristics were evaluated both for a feed velocityof the gypsum slurry into the second feed inlet 325 of 2.50 m/s and of3.55 m/s. At each location L₁₋₁₆, the following flow characteristicswere determined: area-weighted average velocity (U), area-weightedaverage shear rate ({dot over (γ)}), viscosity calculated using thePower Law Model (Eq. 2), shear stress (Eq. 3), and Reynolds Number (Re)(Eq. 4). Using the inlet conditions, dimensionless values of the flowcharacteristics for each location L₁₋₁₆ were determined, as shown inTable III.

For both flow conditions where K was set equal to 100, the averagevelocity was reduced from the first location L₁ at the second feed inlet325 to the sixteenth location L₁₆ at the half portion 1217 of thedistribution outlet 330 of the distribution conduit 328. In theillustrated embodiment, the average velocity was reduced by about ⅕. Theresults for average velocity, on a dimensionless basis, weresubstantially the same as those in Example 2 and FIG. 35.

For both flow conditions, the shear rate increased from the firstlocation L₁ at the second feed inlet 325 to the sixteenth location L₁₆at the half portion 1217 of the distribution outlet 330 of thedistribution conduit 328. In the illustrated embodiment, the shear rateapproximately doubled from the first location L₁ at the second feedinlet 325 to the sixteenth location L₁₆ at the half portion 1217 of thedistribution outlet 330 of the distribution conduit 328. The results forshear rate, on a dimensionless basis, were substantially the same asthose in Example 2 and FIG. 36.

For both flow conditions, the calculated viscosity was reduced from thefirst location L₁ at the second feed inlet 325 to the sixteenth locationL₁₆ at the half portion 1217 of the distribution outlet 330 of thedistribution conduit 328. In the illustrated embodiment, the calculatedviscosity was reduced from the first location L₁ at the second feedinlet 325 to the sixteenth location L₁₆ at the half portion 1217 of thedistribution outlet 330 of the distribution conduit 328 by about half.The results for the calculated viscosity, on a dimensionless basis, weresubstantially the same as those in Example 2 and FIG. 37.

For both flow conditions, the shear stress increased from the firstlocation L₁ at the second feed inlet 325 to the sixteenth location L₁₆at the half portion 1217 of the distribution outlet 330 of thedistribution conduit 328. In the illustrated embodiment, the shearstress increased by about 10% from the first location L₁ at the secondfeed inlet 325 to the sixteenth location L₁₆ at the half portion 1217 ofthe distribution outlet 330 of the distribution conduit 328. The resultsfor the shear stress, on a dimensionless basis, were substantially thesame as those in Example 2 and FIG. 38.

For both flow conditions, the Reynolds number was reduced from the firstlocation L₁ at the second feed inlet 325 to the sixteenth location L₁₆at the half portion 1217 of the distribution outlet 330 of thedistribution conduit 328. In the illustrated embodiment, the Reynoldsnumber was reduced from the first location L₁ at the second feed inlet325 to the sixteenth location L₁₆ at the half portion 1217 of thedistribution outlet 330 of the distribution conduit 328 by about ⅓. Forboth flow conditions, the Reynolds number at the sixteenth location L₁₆at the half portion 1217 of the distribution outlet 330 of thedistribution conduit 328 is in the laminar region. The results for theReynolds number, on a dimensionless basis, were substantially the sameas those in Example 2 and FIG. 39.

FIGS. 34-38 are graphs of the flow characteristics computed for thedifferent flow conditions of Examples 2 and 3. Curve-fit equations wereused to describe the change in the flow characteristics over thedistance between the feed inlet to the half portion of the distributionoutlet. Accordingly, the Examples show that the flow characteristics areconsistent over variations in inlet velocity and/or viscosity.

TABLE III DIMENSIONLESS FLOW CHARACTERISTICS (K = 100) Inlet Velocity =2.50 m/s Inlet Velocity = 3.55 m/s Shear Calc Shear Shear Calc ShearLocation Velocity Rate Visc. Stress Re Velocity Rate Visc. Stress Re L11.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 1.00 L2 1.00 1.16 0.88 1.021.13 1.00 1.21 0.85 1.03 1.18 L3 1.10 1.35 0.77 1.04 1.32 1.10 1.39 0.751.04 1.35 L4 1.00 1.28 0.80 1.03 1.17 1.00 1.35 0.77 1.04 1.22 L5 0.871.15 0.88 1.02 0.94 0.86 1.23 0.84 1.03 0.99 L6 0.83 1.18 0.87 1.02 0.830.83 1.27 0.81 1.03 0.88 L7 0.90 1.60 0.66 1.06 0.93 0.90 1.70 0.63 1.070.98 L8 0.90 1.70 0.63 1.07 0.84 0.90 1.77 0.61 1.08 0.87 L9 0.82 1.610.66 1.07 0.69 0.82 1.71 0.63 1.07 0.73 L10 0.77 1.57 0.68 1.06 0.620.77 1.67 0.64 1.07 0.66 L11 0.76 1.76 0.61 1.08 0.60 0.76 1.88 0.581.09 0.64 L12 0.78 1.79 0.60 1.08 0.61 0.78 1.90 0.57 1.09 0.64 L13 0.781.81 0.60 1.08 0.62 0.78 1.93 0.57 1.09 0.65 L14 0.78 1.84 0.59 1.080.63 0.78 1.94 0.56 1.09 0.66 L15 0.78 1.80 0.60 1.08 0.62 0.78 1.900.57 1.09 0.64 L16 0.79 1.87 0.58 1.09 0.64 0.79 1.96 0.56 1.09 0.67

All references, including publications, patent applications, andpatents, cited herein are hereby incorporated by reference to the sameextent as if each reference were individually and specifically indicatedto be incorporated by reference and were set forth in its entiretyherein.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the invention (especially in the context of thefollowing claims) are to be construed to cover both the singular and theplural, unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. Recitation of ranges of valuesherein are merely intended to serve as a shorthand method of referringindividually to each separate value falling within the range, unlessotherwise indicated herein, and each separate value is incorporated intothe specification as if it were individually recited herein. All methodsdescribed herein can be performed in any suitable order unless otherwiseindicated herein or otherwise clearly contradicted by context. The useof any and all examples, or exemplary language (e.g., “such as”)provided herein, is intended merely to better illuminate the inventionand does not pose a limitation on the scope of the invention unlessotherwise claimed. No language in the specification should be construedas indicating any non-claimed element as essential to the practice ofthe invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate, and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

What is claimed is:
 1. A slurry distributor comprising: a feed conduitincluding a first entry segment with a first feed inlet and a secondentry segment with a second feed inlet disposed in spaced relationshipto the first feed inlet; and a distribution conduit extending generallyalong a longitudinal axis and including an entry portion and adistribution outlet in fluid communication with the entry portion, theentry portion in fluid communication with the first and second feedinlets of the feed conduit, the distribution outlet extending apredetermined distance along a transverse axis, the transverse axisbeing substantially perpendicular to the longitudinal axis; wherein thefirst and second feed inlets each has an opening with a cross-sectionalarea, and the entry portion of the distribution conduit has an openingwith a cross-sectional area which is greater than the sum of thecross-sectional areas of the openings of the first and second feedinlets the distribution outlet of the distribution conduit has anopening with a cross-sectional area which is greater than the sum of thecross-sectional areas of the openings of the first and second feedinlets, and the cross-sectional area of the openings of the entryportion of the distribution conduit is greater than the cross-sectionalarea of the opening of the distribution outlet wherein the feed conduitincludes first and second feed outlets, the first and second feedoutlets in fluid communication with the first and second feed inlets,respectively, the first and second feed outlets in fluid communicationwith the entry portion of the distribution conduit, the first and secondfeed outlets each having an opening with a cross-sectional area that islarger than the cross-sectional area of the opening of the first feedinlet and the second feed inlet, respectively, and the opening of eachof the first and second feed outlets having a hydraulic diameter that issmaller than the hydraulic diameter of the opening of the first feedinlet and the second feed inlet, respectively.
 2. The slurry distributorof claim 1, wherein the first and second feed inlets and the first andsecond entry segments are disposed at a respective feed angle in a rangeup to about 135° with respect to the longitudinal axis.
 3. The slurrydistributor of claim 1, wherein the feed conduit includes a bifurcatedconnector segment including first and second guide surfaces, the firstand second guide surfaces respectively adapted to redirect a first flowof slurry moving in a first feed flow direction through the first inletand the first entry segment by a change in direction angle in a range upto about 135° to an outlet flow direction and adapted to redirect asecond flow of slurry moving in a second feed flow direction through thesecond inlet and the second entry segment by a change in direction anglein a range up to about 135° to the outlet flow direction.
 4. The slurrydistributor of claim 1, wherein the feed conduit includes a guidechannel configured to have a larger cross-sectional area than anadjacent portion of the feed conduit to promote flow of slurry throughthe guide channel, the guide channel disposed adjacent a wall surface.5. The slurry distributor of claim 1, wherein the opening of thedistribution outlet has a width, along the transverse axis, and aheight, along a vertical axis mutually perpendicular to the longitudinalaxis and the transverse axis, wherein the width-to-height ratio of theopening of the distribution outlet is about 4 or more.
 6. The slurrydistributor of claim 1, wherein at least one of the feed conduit and thedistribution conduit includes an area of expansion having across-sectional flow area that is greater than a cross-sectional flowarea of an adjacent area upstream from the area of expansion in adirection from the feed conduit toward the distribution conduit.
 7. Theslurry distributor of claim 1, further comprising: a profiling systemadapted to vary the shape and/or size of the distribution outlet alongthe transverse axis.
 8. A cementitious slurry distributor comprising: afeed conduit including a first entry segment with a first feed inlet anda second entry segment with a second feed inlet disposed in spacedrelationship to the first feed inlet; a distribution conduit extendinggenerally along a longitudinal axis and including an entry portion and adistribution outlet in fluid communication with the entry portion, theentry portion in fluid communication with the first and second feedinlets of the feed conduit; and at least one support segment, eachsupport segment being movable over a range of travel such that thesupport segment is in a range of positions over which the supportsegment is in increasing compressive engagement with a portion of anexterior surface of at least one of the feed conduit and thedistribution conduit.
 9. The slurry distributor of claim 8, furthercomprising: a support system including a support member and a movablesupport assembly, the support member defining a supporting surfaceconfigured to substantially conform to at least a portion of theexterior surface of at least one of the feed conduit and thedistribution conduit, and the movable support assembly including aplurality of support segments, each support segment being movable over arange of travel such that the support segment is in a range of positionsover which the support segment is in increasing compressive engagementwith a portion of the exterior surface of at least one of the feedconduit and the distribution conduit.
 10. The slurry distributor ofclaim 9, wherein said at least one support segment comprises at leasttwo support segments, and at least one support segment is independentlymovable relative to another support segment.
 11. The slurry distributorof claim 9, the movable support assembly includes a support framemovably supporting the support segments.
 12. The slurry distributor ofclaim 11, wherein the movable support assembly includes a clampingmechanism associated with each support segment, each clamping mechanismadapted to selectively retain the associated support segment in aselected position relative to the support frame.
 13. The slurrydistributor of claim 8, wherein each support segment includes acontacting surface configured to substantially conform to a surfaceportion of at least one of the feed conduit and the distributionconduit.
 14. A gypsum slurry mixing and dispensing assembly comprising:a gypsum slurry mixer adapted to agitate water and calcined gypsum toform an aqueous calcined gypsum slurry, the gypsum slurry mixerincluding a housing and an agitator, the housing defining a mixingchamber, a water inlet, and a calcined gypsum inlet, the water inlet andthe calcined gypsum inlet in communication with the mixing chamber, andthe agitator rotatably mounted within the mixing chamber; a slurrydistributor in fluid communication with the gypsum slurry mixer, theslurry distributor including: a feed conduit including a first entrysegment with a first feed inlet and a second entry segment with a secondfeed inlet disposed in spaced relationship to the first feed inlet, thefirst feed inlet adapted to receive a first flow of aqueous calcinedgypsum slurry from the gypsum slurry mixer, the second feed inletadapted to receive a second flow of aqueous calcined gypsum slurry fromthe gypsum slurry mixer, and a distribution conduit extending generallyalong a longitudinal axis and including an entry portion and adistribution outlet in fluid communication with the entry portion, theentry portion in fluid communication with the first and second feedinlets of the feed conduit, the distribution outlet extending apredetermined distance along a transverse axis, the transverse axisbeing substantially perpendicular to the longitudinal axis, thedistribution outlet in fluid communication with both the first and thesecond feed inlets and adapted such that the first and second flows ofaqueous calcined gypsum slurry discharge from the slurry distributorthrough the distribution outlet, wherein the first and second feedinlets each has an opening with a cross-sectional area, and the entryportion of the distribution conduit has an opening with across-sectional area which is greater than the sum of thecross-sectional areas of the openings of the first and second feedinlets.
 15. The gypsum slurry mixing and dispensing assembly of claim14, further comprising: a delivery conduit disposed between and in fluidcommunication with the gypsum slurry mixer and the slurry distributor,the delivery conduit including a main delivery trunk and first andsecond delivery branches; a flow splitter joining the main deliverytrunk and the first and second delivery branches, the flow splitterdisposed between the main delivery trunk and the first delivery branchand between the main delivery trunk and the second delivery branch;wherein the first delivery branch is in fluid communication with thefirst feed inlet of the slurry distributor, and the second deliverybranch is in fluid communication with the second feed inlet of theslurry distributor.
 16. The gypsum slurry mixing and dispensing assemblyof claim 14, wherein the distribution outlet of the distribution conduitof the slurry distributor has an opening with a cross-sectional areawhich is greater than the sum of the cross-sectional areas of theopenings of the first and second feed inlets.
 17. The gypsum slurrymixing and dispensing assembly of claim 16, wherein the cross-sectionalarea of the opening of the entry portion of the distribution conduit ofthe slurry distributor is greater than the cross-sectional area of theopening of the distribution outlet.
 18. The gypsum slurry mixing anddispensing assembly of claim 17, wherein the feed conduit of the slurrydistributor includes first and second feed outlets, the first and secondfeed outlets in fluid communication with the first and second feedinlets, respectively, the first and second feed outlets in fluidcommunication with the entry portion of the distribution conduit, thefirst and second feed outlets each having an opening with across-sectional area that is larger than the cross-sectional area of theopening of the first feed inlet and the second feed inlet, respectively,and the opening of each of the first and second feed outlets having ahydraulic diameter that is smaller than the hydraulic diameter of theopening of the first feed inlet and the second feed inlet, respectively.19. The gypsum slurry mixing and dispensing assembly of claim 14,wherein the feed conduit of the slurry distributor includes a guidechannel configured to have a larger cross-sectional area than anadjacent portion of the feed conduit to promote flow of slurry throughthe guide channel, the guide channel disposed adjacent a wall surface.20. The gypsum slurry mixing and dispensing assembly of claim 14,wherein the distribution outlet of the distribution conduit of theslurry distributor has an opening with a width, along the transverseaxis, and a height, along a vertical axis mutually perpendicular to thelongitudinal axis and the transverse axis, wherein the width-to-heightratio of the outlet opening is about 4 or more.
 21. The gypsum slurrymixing and dispensing assembly of claim 20, wherein the width-to-heightratio of the outlet opening is in a range between 4 and
 288. 22. Thegypsum slurry mixing and dispensing assembly of claim 14, wherein thefeed conduit of the slurry distributor includes a bifurcated connectorsegment including first and second guide surfaces, the first and secondguide surfaces respectively adapted to redirect a first flow of slurrymoving in a first feed flow direction through the first inlet and thefirst entry segment by a change in direction angle in a range up toabout 135° to an outlet flow direction and adapted to redirect a secondflow of slurry moving in a second feed flow direction through the secondinlet and the second entry segment by a change in direction angle in arange up to about 135° to the outlet flow direction.
 23. The gypsumslurry mixing and dispensing assembly of claim 14, wherein at least oneof the feed conduit and the distribution conduit of the slurrydistributor includes an area of expansion having a cross-sectional flowarea that is greater than a cross-sectional flow area of an adjacentarea upstream from the area of expansion in a direction from the feedconduit toward the distribution conduit.
 24. The gypsum slurry mixingand dispensing assembly of claim 14, wherein the distribution conduit ofthe slurry distributor includes a converging portion having a heightthat is smaller than a height in an adjacent region effective toincrease a local shear applied to a flow of aqueous calcined gypsumslurry passing through the converging portion relative to a local shearapplied in the adjacent region.